Journal articles on the topic 'Plates (Engineering) Cracking Mathematical models'
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1
GIORGI, C. "Mathematical models of thin thermoviscoelastic plates." Quarterly Journal of Mechanics and Applied Mathematics 53, no. 3 (September 1, 2000): 363–74. http://dx.doi.org/10.1093/qjmam/53.3.363.
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Karpiuk, Vasyl, Yuliia Somina, Fedir Karpiuk, and Irina Karpiuk. "Peculiar aspects of cracking in prestressed reinforced concrete T-beams." Acta Polytechnica 61, no. 5 (October 31, 2021): 633–43. http://dx.doi.org/10.14311/ap.2021.61.0633.
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In order to study the cracking of prestressed reinforced concrete T-shaped beam structures, the authors planned and carried out a full-scale experiment with five variable factors. The following factors were chosen as variable factors: the relative span of the shear, the ratio of the table overhang width to the thickness of the beam rib, the ratio of the table overhang thickness to the working height of the beam section, the coefficient of transverse reinforcement, the level of prestressing in the working reinforcement. The article describes the cracking process and the destruction of test beams. It was found that the loading level of an opening of inclined cracks is 53% larger than the loading level of a normal crack opening. Mathematical models of bending moments and transverse forces of cracking were built using the “COMPEX” software. Also, the mathematical models of the crack opening width and the projection length of a dangerous inclined crack were obtained. These models are based on the experimental data. Analysing the obtained models, the complex influence of variable factors on the main parameters of crack formation and crack resistance was established. In particular, it was found that the prestress level in the working reinforcement has the greatest effect on the bending moment of cracking. In this case, the value of the shear force of cracking significantly depends on both the prestressing level in the reinforcement and the relative span of the shear. On the basis of the experimental data, the empirical expression is obtained for determining the projection of a dangerous inclined crack for prestressed reinforced concrete T-shaped beams. The resulting equation can be used to calculate a shear reinforcement.
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Prysiazhnyi, Andrii H., Volodymyr V. Kukhar, Vadym Hornostai, Ekaterina Kudinova, Maryna Korenko, and Oleksandr S. Anishchenko. "Mathematical Models for Forecasting of 10Mn2VNb Steel Heavy Plates Mechanical Properties." Materials Science Forum 1045 (September 6, 2021): 237–45. http://dx.doi.org/10.4028/www.scientific.net/msf.1045.237.
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The problem urgency for determining the optimal rolling and heat treatment schedules for providing the required indices of heavy plates physical and mechanical properties is shown. The use of statistical mathematical models for solving this problem is substantiated and the methodology for their design is described. Statistical mathematical models were designed using the mathematical statistics methods and Data Mining tools to determine the yield strength, ultimate tensile strength and percent elongation for 10Mn2VNb steel plates rolled under 3600 heavy plate mill conditions. Software for the numerical implementation of these statistical mathematical models has been developed. Applied software has been developed for the numerical implementation of the statistical mathematical models for predicting the heavy plate’s mechanical properties, and high calculation accuracy has been confirmed with the ones help: 95.82% for the yield strength, 96.78% for the ultimate tensile strength, and 91.48% for the percent elongation. The regularities of the influence for finish rolling factual temperature in the finishing stand of 3600 heavy plate mill and the plate thickness on 10Mn2VNb pipe steel physical and mechanical properties were identified by processing the database and using the designed software.
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Changjun, Cheng, and Yang Xiao. "The mathematical models and generalized variational principles of nonlinear analysis for perforated thin plates." Applied Mathematics and Mechanics 17, no. 2 (February 1996): 109–18. http://dx.doi.org/10.1007/bf00122305.
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Cole, I. S., and D. A. Paterson. "Mathematical models of dependence of surface temperatures of exposed metal plates on environmental parameters." Corrosion Engineering, Science and Technology 41, no. 1 (March 2006): 67–76. http://dx.doi.org/10.1179/174327806x94045.
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Krysko, A. V., J. Awrejcewicz, K. S. Bodyagina, M. V. Zhigalov, and V. A. Krysko. "Mathematical modeling of physically nonlinear 3D beams and plates made of multimodulus materials." Acta Mechanica 232, no. 9 (June 26, 2021): 3441–69. http://dx.doi.org/10.1007/s00707-021-03010-8.
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AbstractIn this work, mathematical models of physically nonlinear plates and beams made from multimodulus materials are constructed. Our considerations are based on the 3D deformation theory of plasticity, the von Mises plasticity criterion and the method of variable parameters of the theory of elasticity developed by Birger. The proposed theory and computational algorithm enable for solving problems of three types of boundary conditions, edge conditions and arbitrary lateral load distribution. The problem is solved by the finite element method (FEM), and its convergence and the reliability of the results are investigated. Based on numerical experiments, the influence of multimodulus characteristics of the material of the beam and the plate on their stress–strain states under the action of transverse loads is illustrated and discussed.
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Krysko, A. V., J. Awrejcewicz, K. S. Bodyagina, and V. A. Krysko. "Mathematical modeling of planar physically nonlinear inhomogeneous plates with rectangular cuts in the three-dimensional formulation." Acta Mechanica 232, no. 12 (November 16, 2021): 4933–50. http://dx.doi.org/10.1007/s00707-021-03096-0.
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AbstractMathematical models of planar physically nonlinear inhomogeneous plates with rectangular cuts are constructed based on the three-dimensional (3D) theory of elasticity, the Mises plasticity criterion, and Birger’s method of variable parameters. The theory is developed for arbitrary deformation diagrams, boundary conditions, transverse loads, and material inhomogeneities. Additionally, inhomogeneities in the form of holes of any size and shape are considered. The finite element method is employed to solve the problem, and the convergence of this method is examined. Finally, based on numerical experiments, the influence of various inhomogeneities in the plates on their stress–strain states under the action of static mechanical loads is presented and discussed. Results show that these imbalances existing with the plate’s structure lead to increased plastic deformation.
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Liu, Nian, Nansheng Qiu, Zhenming Li, Chuan Cai, Xinjie Shan, Ting Gao, and Yuanjie Wang. "Significance and evolution characteristics of the isobutane/n-butane ratio of natural gas." Energy Exploration & Exploitation 38, no. 2 (October 15, 2019): 494–518. http://dx.doi.org/10.1177/0144598719880648.
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In previous studies, two conflicting conclusions existed, which were: (a) the isobutane/n-butane ratio of natural gas increases with the increasing maturity (Ro) of source rocks and (b) decreases with the increasing Ro. In this paper, the correlations between the isobutane/n-butane ratios, dryness of natural gases, and the Ro values of source rocks of 77 gas samples from Cretaceous and Tertiary in Kuqa Depression, Tarim Basin, Triassic Xujiahe Formation in central Sichuan Basin, Carboniferous–Permian in Sulige and Yulin gas field, Ordos Basin, China, and 80 shale gas samples from Mississippian Barnett Shale in the Fort Worth Basin, the United States are analyzed to reveal the evolution of the isobutane/n-butane ratios, then mathematical models of the isobutane/n-butane ratios and Ro are attempted to be established. Results show that the isobutane/n-butane ratio initially increases and then decreases with increasing Ro, both coal-derived gas and oil-type gas. Diverse types of kerogens may be responsible for the different corresponding Ro values when the isobutane/n-butane ratios of gases reach their maximum values. The initial increase in the isobutane/n-butane ratios with increasing Ro is the reason that isobutane is mainly generated at a higher rate by carbonium ion reaction of α-olefins with protons during kerogen primary cracking at lower maturity, whereas free radical reactions to form n-butane relatively quickly during oil cracking at higher maturity and isobutane cracked at a higher rate during the wet gas cracking stage may result in the terminal decreases in the isobutane/n-butane ratios. Besides, mathematical models of the isobutane/n-butane ratios of different types of natural gas and maturity are established. Therefore, the maturity of gas source rock can be obtained quickly based on the models using the isobutane/n-butane ratio combined with other component information (such as dryness, wetness, etc.), which is of great significance to the characterization of natural gas maturity and gas source rock correlation.
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Nguyen, N. T., D. J. Oehlers, and M. A. Bradford. "Models for the Flexural Peeling of Angle Plates Adhesively Bonded to R-C Beams." Advances in Structural Engineering 1, no. 4 (October 1998): 287–300. http://dx.doi.org/10.1177/136943329800100405.
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The strength and stiffness of existing reinforced concrete beams may be enhanced by adhesively bonding angle section members to the soffit/side edges of reinforced concrete (RC) beams. This retrofitting is extremely important in improving the seismic performance of under reinforced RC beams which may suffer ductility problems in earthquakes, or whose strength has deteriorated due to unfavourable environmental factors. This paper develops generic mathematical models for simulating the debonding of angle plates glued to the edges of RC beams as a result of flexural peeling. It is shown that to achieve an accurate model the derivations are quite complex, but the experimental calibration renders the presentation of the model in a simple format. The models have been validated with experimental results.
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Verdério Júnior, S. A., V. L. Scalon, S. R. Oliveira, P. C. Mioralli, and E. Avallone. "DIMENSIONLESS PHYSICAL-MATHEMATICAL MODELING OF TURBULENT NATURAL CONVECTION." Revista de Engenharia Térmica 20, no. 3 (October 10, 2021): 37. http://dx.doi.org/10.5380/reterm.v20i3.83269.
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Natural convection heat transfer is present in the most diverse applications of Thermal Engineering, such as in electronic equipment, transmission lines, cooling coils, biological systems, etc. The correct physical-mathematical modeling of this phenomenon is crucial in the applied understanding of its fundamentals and the design of thermal systems and related technologies. Dimensionless analyses can be applied in the study of flows to reduce geometric and experimental dependence and facilitate the modeling process and understanding of the main influence physical parameters; besides being used in creating models and prototypes. This work presents a methodology for dimensionless physical-mathematical modeling of natural convection turbulent flows over isothermal plates, located in an “infinite” open environment. A consolidated dimensionless physical-mathematical model was defined for the studied problem situation. The physical influence of the dimensionless numbers of Grashof, Prandtl, and Turbulent Prandtl was demonstrated. The use of the Theory of Dimensional Analysis and Similarity and its application as a tool and numerical device in the process of building and simplifying CFD simulations were discussed.
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Zaoui, Fatima Zohra, Djamel Ouinas, Belkacem Achour, Mabrouk Touahmia, Mustapha Boukendakdji, Enamur R. Latifee, Ahmed A. Alawi Al-Naghi, and Jaime Aurelio Viña Olay. "Mathematical Approach for Mechanical Behaviour Analysis of FGM Plates on Elastic Foundation." Mathematics 10, no. 24 (December 15, 2022): 4764. http://dx.doi.org/10.3390/math10244764.
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This paper presents the flexural analysis of functionally graded plates resting on elastic foundations using new two-dimensional (2D) and quasi-three-dimensional (quasi-3D) higher order shear deformation theories. The main interesting feature of this theory is that it proposes a new displacement field with undetermined integral variables which involves only five unknown functions, unlike other shear and normal deformation theories, hence making it easier to use. A parabolic transverse shear deformation shape function satisfying the zero shear stress conditions on the plate outer surfaces is considered. The elastic foundation follows the Pasternak mathematical model. The material properties change continuously across the thickness of the FG plate using different distributions: power law, exponential, and Mori–Tanaka models. The governing equations of FG plates subjected to sinusoidal and uniformly distributed loads are established through the principle of virtual works and then solved via Navier’s procedure. In this work, a detailed discussion on the influence of material composition, geometric parameters, stretching effect, and foundation parameters on the deflection, axial displacements, and stresses is given, and the obtained results are compared with those published in previous works to demonstrate the accuracy and the simplicity of the present formulations. The different obtained results were found to be in good agreement with the available solutions of other higher-order theories. The proposed model is able to represent the cross section warping in the deformed shape and to demonstrate the validity and efficiency of the approach, the findings reported herein prove that this theory is capable of predicting displacements and stresses more accurately than other theories, as its results are closer when compared to numerical methods reported in other literatures.
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Haffar, Muhammad Ziad, Balázs Kövesdi, and Sándor Adany. "Buckling of compressed plates with closed-section longitudinal stiffeners: Two new mathematical models for resistance prediction." Structures 33 (October 2021): 3526–39. http://dx.doi.org/10.1016/j.istruc.2021.06.083.
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Javadi, Masoud, Erick I. Saavedra Saavedra Flores, Sergio J. Yanez, Siva Avudaiappan, Juan C. Pina, and Carlos F. Guzmán. "Investigation of the Influence of Design Parameters on the Strength of Steel–Concrete Composite Shear Walls by Finite Element Simulations." Buildings 13, no. 1 (January 10, 2023): 187. http://dx.doi.org/10.3390/buildings13010187.
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In this paper, the influence of design parameters on the strength of steel–concrete composite shear walls is investigated by means of finite element (FE) simulations. The shear wall typology studied in this paper consists of multiple composite plate shear wall-concrete encased on one or both sides of the plates. The FE models include contact technology to capture debonding between concrete and steel, tensile cracking in concrete, and large deflection theory involving local instabilities. Some design parameters considered in this work are the height-to-width ratio of the steel plates and their thickness, number of steel plates, the cross-section of the columns, and the height-to-width ratio of the shear wall. Furthermore, a sensitivity analysis of the normalised shear strength per unit cost of structure for these design parameters is also studied. Our numerical predictions are validated successfully with experimental data reported in the literature, revealing the predictive capabilities of the model. The present results provide further insight into the structural behavior of steel–concrete composite shear walls and pave the way for the future development of more efficient and innovative steel–concrete composite systems.
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Aidossov, Allayarbek, Galym Aidosov, and Saltanat Narbayeva. "Construction of mathematical models of the stressed-strained state of a material with a porous water-saturated base under dynamic load." Eastern-European Journal of Enterprise Technologies 5, no. 7 (113) (October 29, 2021): 25–35. http://dx.doi.org/10.15587/1729-4061.2021.238978.
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Materials of beams, plates, slabs, strips have been commonly applied in various fields of industry and agriculture as flat elements in the structures for machinery and construction. They are associated with the design of numerous engineering structures and facilities, such as the foundations of various buildings, airfield and road surfaces, floodgates, including underground structures. This paper reports a study into the interaction of the material (of beams, plates, slabs, strips) with the deformable base as a three-dimensional body and in the exact statement of a three-dimensional problem of mathematical physics under dynamic loads. The tasks of studying the interaction of a material (beams, plates, slabs, strips) with a deformable base have been set. A material lying on a porous water-saturated viscoelastic base is considered as a viscoelastic layer of the same geometry. It is assumed that the lower surface of the layer is flat while the upper surface, in a general case, is not flat and is given by some equation. Classical approximate theories of the interaction of a layer with a deformable base, based on the Kirchhoff hypothesis, have been considered. Using the well-known hypothesis by Timoshenko and others, the general three-dimensional problem is reduced to a two-dimensional one relative to the displacement of points of the median plane of the layer, which imposes restrictions on external efforts. In the examined problem, there is no median plane. Therefore, as the desired values, displacements and deformations of the points in the plane have been considered, which, under certain conditions, pass into the median plane of the layer. It is not possible to find a closed analytical solution for most problems while experimental studies often turn out to be time-consuming and dangerous processes
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Kaklauskas, Gintaris. "METHODS AND CONSTITUTIVE MODELS FOR DEFORMATIONAL ANALYSIS OF FLEXURAL REINFORCED CONCRETE MEMBERS/LENKIAMŲJŲ GELŽBETONINIŲ ELEMENTŲ DEFORMATYVUMO VERTINIMO METODAI IR FIZIKINIAI MODELIAI." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 6, no. 5 (October 31, 2000): 329–38. http://dx.doi.org/10.3846/13921525.2000.10531610.
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The paper reviews both analytical and finite element methods for deformational analysis of flexural reinforced concrete members subjected to short-term loading. In a state-of-the-art summary of various proposed stress-strain relationships for concrete and reinforcement, a special emphasis is made on critical survey of modelling post-cracking behaviour of tensile concrete in smeared crack approach. Empirical code methods of different countries (American Code (ACI Committee 318 [7]), the Eurocode EC2 [8], and the Russian (old Soviet) Code (SNiP 2.03.01-84 [5]) for deflection calculation of flexural reinforced concrete members are briefly described in section 2. Although these methods are based on different analytical approaches, all of them proved to be accurate tools for deflection assessment of members with high and average reinforcement ratios. It should be noted that these methods have quite a different level of complexity since the Russian Code method employs a great number of parameters and expressions whereas the ACI and EC2 methods are simple and include only basic parameters. Approaches of numerical simulation and constitutive relationships are discussed in Chapter 3. All numerical simulation research can be classified into two large groups according to two different approaches for crack modelling (subsection 3.1): 1) Discrete cracking model. In this approach, cracks are traced individually as they progressively alter the topology of the structure. 2) Smeared cracking model. The cracked concrete is assumed to remain a continuum, ie the cracks are smeared out in the continuous fashion. After cracking, the concrete becomes orthotropic with one of the material axes being oriented along the direction of cracking. Constitutive relationships for steel and plain concrete are presented in subsection 3.2. A special emphasis is made on critical survey of modelling post-cracking behaviour of tensile concrete in smeared crack approach. It has been concluded that although empirical design codes of different countries ensure safe design, they do not reveal the actual stress-strain state of cracked structures and often lack physical interpretation. Numerical methods which were rapidly progressing within last three decades are based on universal principles and can include all possible effects such as material nonlinearities, concrete cracking, creep and shrinkage, reinforcement slip, etc. However, the progress is mostly related to the development of mathematical apparatus, but not material models or, in other words, the development was rather qualitative than quantitative. Constitutive relationships often are too simplified and do not reflect complex multi-factor nature of the material. Existing constitutive relationships for concrete in tension do not assure higher statistical accuracy of deflection estimates for flexural reinforced concrete members in comparison to those obtained by empirical code methods. The author has developed integral constitutive model for deformational analysis of flexural reinforced concrete members [36]. The integral constitutive model consists of traditional constitutive relationships for reinforcement and compressive concrete and the integral constitutive relationship for cracked tensile concrete which accumulates cracking, tension stiffening, reinforcement slippage and shrinkage effects. This constitutive model can be applied not only in a finite element analysis, but also in a simple iterative technique based on classical principles of strength of materials extended to layered approach.
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Apostolopoulos, Charis Alk, Konstantinos F. Koulouris, and Alkiviadis Ch Apostolopoulos. "Correlation of Surface Cracks of Concrete due to Corrosion and Bond Strength (between Steel Bar and Concrete)." Advances in Civil Engineering 2019 (February 4, 2019): 1–12. http://dx.doi.org/10.1155/2019/3438743.
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The current experimental study presents the results of bond strength loss (steel bar concrete) due to the corrosion damage of steel bar specimens, semiembedded in concrete, at various times of exposure to corrosive environment. In this case, a correlation was made between the width of the surface cracks of concrete caused by reinforcing steel corrosion and bond strength for different distances between stirrups and different cover thickness of concrete. The study indicates close relationship between the width of surface cracking, the percentage mass loss of embedded reinforcing bar, the distance between stirrups, and the cover thickness. In addition, mathematical predictive models of bond strength loss of corroded specimens were proposed. The model outcomes showed that the cracking development on concrete surface up to a width of 1.6 mm is accompanied by an exponential reduction of bond strength loss between steel reinforcement and concrete. Furthermore, the investigation has shown that the increase of transverse reinforcement (stirrups) percentage and the cover thickness play a significant role in durability of reinforced concrete elements and in bond strength maintenance between rebar and concrete.
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Wen, Guojun, Haojie Liu, Hongbo Huang, Yudan Wang, and Xinyu Shi. "Meshless method simulation and experimental investigation of crack propagation of CBM hydraulic fracturing." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 73 (2018): 72. http://dx.doi.org/10.2516/ogst/2018074.
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For simulating CoalBed Methane (CBM) hydraulic fracturing using 3-D meshless method, this paper analyzed the hydraulic fracturing mechanism and cracking form for coal rock and established the geometric and mathematical models of hydraulic fracturing propagation in coal rock in terms of the Hillerborg model on crack opening displacement theory. With the theoretical basis of hydromechanics, the formulas for calculating hydraulic pressure inside the fracture by numerical simulation were deduced from the analysis on this fluid-structure interaction problem. The geometric and mathematical models established above were described by 3-D meshless Galerkin (EFG, Element-Free Galerkin) method and compiled into the numerical simulation program using VB and FORTRAN programming language to simulate the fracture propagation for an actual coal rock sample with a drilling hole as an example. Then the physical simulation experiment of hydraulic fracturing propagation of coal seam was conducted on the same coal rock sample. Through the direct observation with naked eyes and detection by advanced instruments of ESEM and Micro-CT, the shape and parameters of cracks on the surface of and inside the coal rock sample were achieved, which indicated that experimental results are reasonably consistent with numerical simulation results.
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Resch, M., and R. Scheidl. "A model for fluid stiction of quickly separating circular plates." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 9 (October 31, 2013): 1540–56. http://dx.doi.org/10.1177/0954406213509613.
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Fluid stiction is a force which is created by the average pressure difference between a fluid-filled, narrow, quickly opening gap and the surrounding pressure. It plays a negative role in compressor valve technology and in fast switching valves, since it hinders an immediate response of the valves to a changing driving force situation. In this paper, the axisymmetric fluid stiction problem is studied by analytical mathematical models and experiments performed on a specific test rig. The study shows that the stiction force in narrow gaps is dominated by the viscous flow as described by the Reynolds equation for lubricating gaps and by cavitation which occurs in a centre region if the gap opening speed exceeds a critical value. The cavitation zone first extends and then shrinks and, finally, gives rise to complex oscillation phenomena due to the impact of the fluid when the cavitation zone collapses. It was found experimentally that fluids can create negative pressure for very short time. Measures to limit the stiction force are a large initial gap height or additional fluid supply channels from the surrounding to the gap.
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Muszynska, Agnes. "Vibrational Diagnostics of Rotating Machinery Malfunctions." International Journal of Rotating Machinery 1, no. 3-4 (1995): 237–66. http://dx.doi.org/10.1155/s1023621x95000108.
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This paper outlines rotating machinery malfunction diagnostics using vibration data in correlation with operational process data. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are emphasized. After presenting basic principles of machinery diagnostics, several specific malfunction symptoms supported by simple mathematical models are given. These malfunctions include unbalance, excessive radial load, rotor-to-stator rubbing, fluid-induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions. Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics of rotors is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are discussed. In the Appendix, basic instrumentation for machine monitoring is outlined.
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Maksymenko-Sheiko, Kyrylo V., Tetiana I. Sheiko, Denys O. Lisin, and Nykyta D. Petrenko. "Mathematical and Computer Modeling of the Forms of Multi-Zone Fuel Elements with Plates." Journal of Mechanical Engineering 25, no. 4 (December 30, 2022): 32–38. http://dx.doi.org/10.15407/pmach2022.04.032.
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Seeing the significant increase in the number of nuclear power plants, as well as models and modifications of nuclear reactors, it becomes important to find out/establish the advantages of certain plants. At the same time, designers face a number of questions for which optimal solutions have not yet been found. At nuclear plants, there is the largest turnover of financial funds and the smallest gain in economy brings huge profits, but one should not forget about reliability and costs during the plant construction. This is a complex problem that is solved at the design stage. Calculations of the reactor at the design stage make it possible to determine the main parameters of the active zone, temperature values, etc. Thermohydraulic calculation of the active zone of the reactor is one of the cornerstones in justifying the safe operation of the nuclear power plant. Calculations of coolant parameters and temperatures of fuel elements are carried out at all stages of designing and proving the safety of nuclear power plants. Twisted pipes and finned heat transfer surfaces are widely used in engineering to increase the effective heat transfer coefficient. In particular, longitudinal, transverse, and spiral edges are used for finning the shells of fuel elements of nuclear reactors and the outer surfaces of steam generator pipes. Finning not only increases the heat transfer surface on the side where the heat transfer coefficient has a low value, but also significantly affects the hydrodynamics of the flow, and thus affects this coefficient. It is obvious that the better the medium is mixed in the main flow and in the intercoral zone, the higher the heat transfer coefficient is. The most profitable forms of fuel elements shells finning are chevron and polyzonal finning, which are performed in the form of a multiturn spiral with a large step. The R-function theory turned out to be quite convenient for building mathematical models of finned shells of fuel elements with straight and helical plates, as well as for building the corresponding objects on a 3D printer. From a practical point of view, the relevance of the problem is also determined by the significant spread of twisted cylindrical bodies, twisted channels, coils in the energy, chemical, oil, gas, metallurgical industries and in heat engineering equipment. The flows that arise at this time make it possible to intensify the processes of heat and mass exchange and achieve savings in energy resources
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Grysa, Krzysztof, Artur Maciąg, and Artur Ściana. "Comparison of the Efficiency of Two Types of Heat Exchangers with Parallel Plates Made of Varied Materials." Energies 14, no. 24 (December 19, 2021): 8562. http://dx.doi.org/10.3390/en14248562.
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The paper discusses two mathematical models for the air flow through a plate heat exchanger with parallel plates. The first exhausts the used air and then supplies the fresh air. The second exhausts the used air above the plate and simultaneously supplies fresh air under it (counter-flow exchanger). In both cases, the exhaust air heat is used to heat the supply air. The purpose of the research is to verify which exchanger uses the exhaust air heat more efficiently. The method of the Trefftz function was used to determine approximate solutions of the analysed problems. The results obtained for 1.2 mm thick steel, aluminium, and copper plates and for external winter, summer, and spring–autumn temperatures are discussed. The results indicate that steel is the best material for a plate heat exchanger, and the counter-flow exchanger is more efficient of the two. Thanks to the use of thin steel plates and the reduction of the air exchange time to a few minutes, cheap and efficient counter-flow exchangers can be obtained.
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Богуцкий, Владимир, Vladimir Bogutskiy, С. Братан, S. Bratan, А. Колесов, and A. Kolesov. "Mathematical modeling of high-precision surfaces finishing in elastic plates with surface-active matters." Science intensive technologies in mechanical engineering 1, no. 10 (September 9, 2016): 26–32. http://dx.doi.org/10.12737/21425.
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At present a significant problem at the production of high-precision machinery and devices is the ensuring of stability of quality specified parameters and increase of working productivity. The simultaneous achievement of these values may be obtained only at the expense of the destination of optimum modes and methods of manufacturing operations control for that there were necessary adequate mathematical models. The existing engineering processes are formed on determined procedures without taking into account a stochastic nature of a process and the interference of chemical and mechanical phenomena in the area of working. In the paper the mechanism of allowance removal at finishing with abrasive pastes having in their composition as fillers the surface-active matters as a factor defining the effectiveness of a finishing procedure is investigated. A process mathematical model is developed allowing the computation of material removal at any time at different algorithms of modes changes including parameters of a contact area, a current state of a surface layer in a blank. A model formed taking into account the process of passivation, machine cutting, takes into account a stochastic character of a process and allows estimating differentially the impact of separate factors upon material removal.
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Han, Xue, Anlong Jiang, Jinhuo Zheng, Xiangui Zhou, Yewei Chen, Sibao Fang, Xin Li, Jianhua He, and Haifeng Li. "Seismic Behavior of Box Steel Bridge Pier with Built-In Energy Dissipation Steel Plates." Advances in Materials Science and Engineering 2022 (October 22, 2022): 1–17. http://dx.doi.org/10.1155/2022/4807721.
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Based on the design concept of earthquake-resilient structure, a new-type of box-shaped steel piers with embedded energy-dissipating steel plates was proposed. Quasi-static tests of 6 box-shaped steel pier specimens under variable axial pressure and cyclic horizontal loading were carried out. By analyzing the failure mode, load-displacement hysteretic curve, skeleton curve, displacement ductility coefficient, stiffness degradation characteristics, strength degradation coefficient, and cumulative hysteretic energy, the effects of setting energy-dissipating steel plate, axial compression ratio, and thickness of energy dissipation steel plates on the seismic performance of new-type steel piers were discussed. Finite element models of steel bridge piers were established and compared with the test results. The analysis results using FEM agree well with the test results. Results show that the setting of energy-dissipating steel plates can effectively improve the ductility, deformation capacity, and energy-dissipating capacity of box-shaped steel piers, and effectively delay buckling deformation and cracking of wall plates. The steel plate near the bolt hole of the wall plate at the root of the new-type of box-shaped steel piers is easy to crack due to stress concentration, resulting in a rapid reduction of the maximum bearing capacity of the specimens. With the increase of axial compression ratio, the bearing capacity, energy-dissipating capacity, and earthquake-resilient capacity of the specimens increase. The smaller the thickness of the replaceable energy-dissipating steel plates, the smaller the bearing capacity and faster the stiffness degradation of the specimens become, while the ductility and energy-dissipating capacity of the specimens are improved. The axial compression ratio and the thickness of the energy-dissipating steel plate have relatively little effect on the strength degradation of the specimens. In order to facilitate the popularization and application of the new-type steel piers, formulas were also established to calculate the bearing capacity and displacement ductility factor of the new-type of box-shaped steel piers.
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STAROVOITOV, Eduard I., Denis V. LEONENKO, and Alexander A. OREKHOV. "Bending of an elastoplastic circular sandwich plate on an elastic foundation in a temperature field." INCAS BULLETIN 13, S (August 3, 2021): 233–44. http://dx.doi.org/10.13111/2066-8201.2021.13.s.21.
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Today, the development of the general theory of quasi-static deformation of three-layer structural elements, including plates, is not yet complete and is being intensively studied. Mathematical models of deformation under complex thermo-force and thermo-irradiation loads are created. The problems of strength, stability, and dynamic behaviour are considered. In strength calculations of three-layer structural elements, it is necessary to take kinematic hypotheses for each layer separately, which complicates the mathematical side of the problem but leads to significant refinement of the stress-strain state. The reaction of an elastic foundation is described by the Winkler model. The use of variational methods allows one to obtain a refined system of three differential equations of equilibrium in internal forces. The thermo-force bending of an elastoplastic circular sandwich plate with a light core connected to an elastic foundation is considered. The polyline normal hypotheses are used to describe the kinematics of a plate package that is not symmetric in thickness. In thin base layers, the Kirchhoff-Love hypotheses are accepted. In a light relatively thick core, the Timoshenko hypothesis is true, while the normal remains rectilinear, but rotates at some additional angle, the radial displacements change linearly in thickness. The differential equations of equilibrium are obtained using the Lagrange variation method. The statement of the boundary value problem in displacements is given in a cylindrical coordinate system. Numerical results for circular metal-polymer sandwich plates are presented.
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Craine, R. E., and M. G. Newman. "Modelling creep failure in welded plates under uniaxial loading." Journal of Strain Analysis for Engineering Design 31, no. 2 (March 1, 1996): 117–24. http://dx.doi.org/10.1243/03093247v312117.
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Understanding more fully the behaviour of weldments is important since they can reduce the lifetime of structures at high temperatures, but performance factors are omitted from most existing design codes (with the exception of the high temperature fast reactor codes). Simple mathematical models which produce approximate solutions quickly are useful since they allow the design engineer to carry out rapid simulations. In this paper the ideas of continuum damage mechanics are incorporated into a model, based on the Cosserat theory of plates and a multi-axial version of Norton's creep law, which has been used recently to calculate the steady state creep strain rates in a weldment. Failure results are calculated numerically for a ferritic plate of constant thickness subject to uniaxial loading, the plate containing parent and weld metals, type IV material and a high-temperature heat-affected zone (HAZ). Results obtained for various material parameters and weldment configurations show that rupture times depend strongly on the choice of generalized stress in the damage evolution equation. The results also reveal that changes to the material strength of a region cannot be made in isolation if physically realistic results are to be obtained and, further, that early failures can occur if there are large differences in strength between the various parts of the weldment.
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Ushakov, Andrey, Sophiya Zagrebina, Sergei Aliukov, Anatoliy Alabugin, and Konstantin Osintsev. "A Review of Mathematical Models of Elasticity Theory Based on the Methods of Iterative Factorizations and Fictitious Components." Mathematics 11, no. 2 (January 13, 2023): 420. http://dx.doi.org/10.3390/math11020420.
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This review analyzes articles on mathematical modeling of elasticity theory using iterative factorizations and fictitious components. To carry out this study, various methods are developed, for example, an approximate analytical method of iterative factorizations for calculating the displacements of a rectangular plate, and a modified method of fictitious components for calculating the continuous displacement of plates. The performed calculations confirm the effectiveness of these methods. Descriptions of solutions to problems of elasticity theory and possible applications of the considered mathematical models and methods are given. An overview of the methods used to solve these problems is given. Particular attention is paid to problematic issues that arise in solving these problems. Techniques used to reduce complex problems to the solution of simple problems are given, for example, the lowering of the order of differential equations and the reduction of solutions in complex domains to solutions in a simple domain. For the first approach, iterative factorization methods are often used, and for the second, methods of the fictitious component type are often used. The main presentation in this review is focused on the approximate solution of elliptic boundary value problems. The works considered in the review raise questions about the development of methods in research on fictitious domains, fictitious components, and iterative factorizations.
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Vargas, Rogério Santos, Jonatas Comparin Araldi, Deise Renata Bringmann, Asdrubal Falavigna, and Leandro Luis Corso. "Computer simulation of mechanical strength compared between straight and wave plates for femoral application through finite elements." Research, Society and Development 11, no. 12 (September 15, 2022): e301111234710. http://dx.doi.org/10.33448/rsd-v11i12.34710.
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The objective of this study was to evaluate, by means of computer simulation, the difference in mechanical strength between two plate models straight and wave used in femur fracture fixation, submitting both to a progressive static axial load. There are criteria to evaluate the yield strength of a material: Tresca, Von Mises and Mohr-Coulomb. In this study, the Von-Mises strain criterion theory was used because it is used in fatigue strength tests of ductile materials, in this case, stainless steel. This criterion, indicates that the yielding of a solid material begins when it reaches a critical stress value. The models were built computationally using 3D modeling software. The finite element mathematical method was used to evaluate the stress and strain curve, two elements considered fundamental to verify the behavior of the metal during the application of stress and the displacement of the plates, to thus evaluate the strength of each. The results obtained after the finite element analysis show that the plates do not reach the critical limit for yielding, but the straight plate absorbs 10 times more stress compared to the wave plate. The wave plate allows the conclusion that there is decomposition of the applied force. Both plates remain in the elastic regime with load up to 1000 N. The load is equivalent to the weight of the body and gravity. It was concluded that the axial force applied in the caudal direction decomposes into resulting ones compared to the straight plate, which absorbs all the load and may reach the critical limit for yielding before the wave plate.
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Anatolyevich Treschev, Alexandr, Alexander Anatolyevich Bobryshev, Victor Grigoryevich Telichko, Lenar Nurgaleevich Shafigullin, and Alexander Valeryevich Bashkatov. "Determination of stress-strain state of reinforced slabs from non-linear material taking into account the influence of aggressive environment." Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 27, no. 4 (January 10, 2019): 488–503. http://dx.doi.org/10.22630/pniks.2018.27.4.46.
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In this article, the construction of finite-elemental model of definition of stress-strain state of reinforced concrete plates in conditions of active deformation and simple loading in combination with long-term influence of chloride-containing operating environment. Non-linear behavior of concrete is simulated based on the determining relations proposed by Treschev, cracking and plastic deformations in armature are taken into account. The impact of the aggressive environment is taken into account in accordance with the model proposed by Petrov and Penina. In the article all basic correlations of finite elements method in convenient for software realization on a computer are given. As the object of research for this article is a concrete plate reinforced with steel reinforcement in a stretched area, which is under the joint influence of mechanical load and aggressive chloride-containing environment on the protective polymer–concrete layer. The load was taken evenly distributed across the entire slab area. At the solution of this problem the non-linear sensitivity of the basic material (concrete) to the type of the tense condition, plastic deformations in armature, degradation of a protective concrete at influence of external aggressive environment are taken into account. In the article some especially characteristic results of mathematical modeling of the specified model problem are given. The obtained results of joint influence on the plate of mechanical load and aggressive environment are analyzed.
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Koconis, David B., Låszló P. Kollår, and George S. Springer. "Shape Control of Composite Plates and Shells with Embedded Actuators. I. Voltages Specified." Journal of Composite Materials 28, no. 5 (March 1994): 415–58. http://dx.doi.org/10.1177/002199839402800503.
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The changes in shapes of fiber-reinforced composite beams, plates and shells affected by embedded piezoelectric actuators were investigated. An analytical method was developed which can be used to calculate the changes in shapes for specified applied voltages to the actuators. The method is formulated on the basis of mathematical models using two-dimensional, linear, shallow shell theory including transverse shear effects which are important in the case of sandwich construction. Solutions to the governing equations were obtained via the Ritz method. A computationally efficient computer code with a user-friendly interface was written which is suitable for performing the numerical calculations. The code, designated as SHAPE1, provides the change in shape for specified applied voltages. To validate the method and the computer code, results generated by the code were compared to existing analytical and experimental results and to test data obtained during the course of the present investigation. The predictions provided by the SHAPE1 code were in excellent agreement with the results of the other analyses and data.
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Koconis, David B., Låszló P. Kollår, and George S. Springer. "Shape Control of Composite Plates and Shells with Embedded Actuators. II. Desired Shape Specified." Journal of Composite Materials 28, no. 5 (March 1994): 459–82. http://dx.doi.org/10.1177/002199839402800504.
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The changes in shapes of fiber-reinforced composite beams, plates and shells affected by embedded piezoelectric actuators were investigated. An analytical method was developed to determine the voltages needed to achieve a specified desired shape. The method is formulated on the basis of mathematical models using two-dimensional, linear, shallow shell theory including transverse shear effects which are important in the case of sandwich construction. The solution technique is a minimization of an error function which is a measure of the difference between the deformed shape caused by the application of voltages and the desired shape. A computationally efficient, user-friendly computer code was written which is suitable for performing the numerical calculations. The code, designated as SHAPE2, gives the voltages needed to achieve specified changes in shape. To validate the method and the computer code, results generated by the code were compared to existing analytical and experimental results. The predictions provided by the SHAPE2 code were in excellent agreement with the results of the other analyses and data.
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Akram, Ghazala, Muhammad Abbas, Hira Tariq, Maasoomah Sadaf, Thabet Abdeljawad, and Manar A. Alqudah. "Numerical Approximations for the Solutions of Fourth Order Time Fractional Evolution Problems Using a Novel Spline Technique." Fractal and Fractional 6, no. 3 (March 19, 2022): 170. http://dx.doi.org/10.3390/fractalfract6030170.
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Developing mathematical models of fractional order for physical phenomena and constructing numerical solutions for these models are crucial issues in mathematics, physics, and engineering. Higher order temporal fractional evolution problems (EPs) with Caputo’s derivative (CD) are numerically solved using a sextic polynomial spline technique (SPST). These equations are frequently applied in a wide variety of real-world applications, such as strain gradient elasticity, phase separation in binary mixtures, and modelling of thin beams and plates, all of which are key parts of mechanical engineering. The SPST can be used for space discretization, whereas the backward Euler formula can be used for time discretization. For the temporal discretization, the method’s convergence and stability are assessed. To show the accuracy and applicability of the proposed technique, numerical simulations are employed.
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Lisienkova, Liubov, Tatiana Shindina, Nina Orlova, and Liudmila Komarova. "Optimization of the Concrete Composition Mix at the Design Stage." Civil Engineering Journal 7, no. 8 (August 1, 2021): 1389–405. http://dx.doi.org/10.28991/cej-2021-03091732.
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The problem of the composition optimization of concrete mixes seems to be quite urgent as errors at the composition design stage can lead to problems of concrete at the stage of exploitation such as delamination, cracking etc. Reasonable selection of concrete mix components guarantees the required strength of concrete and reinforced concrete structures in the future. This paper investigates the influence of the concrete mix composition on the strength of concrete. Firstly, typical risks that can occur on the composition design stage have been identified through the experts' interviews. Secondly, this risks were associated with indicators and characteristics that can be tested experimentally. Running of several mathematical models has allowed to outline concrete mix parameters of highest importance and formulate an empirical equation for the dependence of the strength of the concrete mixture on the values of the coarse aggregate quality factor, the fine aggregate fraction and the consumption of the Portland cement has been proposed. As a result, a methodology for controlling the quality of concrete at the stage of the composition design has been formulated. Doi: 10.28991/cej-2021-03091732 Full Text: PDF
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Stara, Marie. "Testing of Pre-Stressing Masonry Wall with Using Different Thickness of Anchor Plates." Advanced Materials Research 1082 (December 2014): 211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.211.
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Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry brick corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB – TU Ostrava for measurement tri-axial stress-strain conditions in masonry. In this brick corner one pre-stressing bar is placed. And on the pre-stressing bar is anchored to the anchor plate which transfer pre-stressing forces to the masonry. The thickness of brick corner is 440mm and anchor plate will be used about thickness 10, 20 and 30mm. Mathematical modelling of brick corner is based on finite element method using software ANSYS and then the results are compared with results of laboratory tests. On the basis of these results it should be possible to improve the models and to approach closer to the accurate and at the same time simple procedure for design of pre-stressed masonry.
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Tekin, Gülçin, and Fethi Kadıoğlu. "Viscoelastic Behavior of Shear-Deformable Plates." International Journal of Applied Mechanics 09, no. 06 (September 2017): 1750085. http://dx.doi.org/10.1142/s1758825117500855.
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The purpose of this study is to extend a new mixed-type finite element (MFE) model, developed earlier by the present authors for the analysis of viscoelastic Kirchhoff plates [Aköz, A. Y., Kadıoğlu, F. and Tekin, G. [2015] “Quasi-static and dynamic analysis of viscoelastic plates”, Mechanics of Time-Dependent Materials 19(4), 483–503], to study the quasi-static and dynamic responses of first-order shear-deformable (FSD) linear viscoelastic Mindlin–Reissner plates. In this context, various viscoelastic material models are discussed for the plate structure to read from them possible patterns of viscoelastic behavior. The developed MFE named VPLT32 is C0-continuous four-node linear isoparametric plate element with eight degrees of freedom per node. Hereditary integral form of the constitutive law with constant Poisson’s ratio is used. A new functional in the Laplace–Carson domain suitable for MFE formulation in the same domain is developed by employing Gâteaux differential (GD) method. The unique aspects of this study and the possible contributions of the proposed method to the literature can be summarized as follows: by using this new functional, moment and shear force values that are important for engineers can be obtained directly without any mathematical operation. In addition, geometric and dynamic boundary conditions can be obtained easily and a field variable can be included to the functional systematically. Moreover, shear-locking problem can be eliminated by using the GD method. Dubner and Abate numerical Laplace inversion technique is adopted to transform the obtained solution from the Laplace–Carson domain into the real-time domain. A set of numerical examples are presented not only to demonstrate the validity and accuracy of the proposed MFE formulation but also to examine the effects of load, geometry and material parameters on the viscoelastic response of FSD Mindlin–Reissner plates and to give a better insight into time-dependent behavior of engineering thick plate problems.
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Jacobsson, H. "Aspects of Disc Brake Judder." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217, no. 6 (June 1, 2003): 419–30. http://dx.doi.org/10.1243/095440703766518069.
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Brake judder is a braking induced, forced vibration occurring in different types of vehicles. The judder frequency is directly proportional to the revolution speed of the wheel and therefore also to the velocity of the vehicle. The driver experiences judder as vibrations in the steering wheel, brake pedal and floor. In the higher frequency range, the structural vibrations are accompanied by a sound. Brake judder primarily affects the comfort but could, when confronting an inexperienced driver for the first time, lead to faulty reactions and reduced driving safety. Furthermore, a specific type of judder, so-called hot judder, is related to disc cracking. There are numerous publications available dealing with high frequency vibrations, such as brake squeal, including mathematical models for analysis and simulation. However, low frequency phenomena, such as brake judder and groan, have received much less attention. There is a growing interest from the automotive industry concerning brake judder. Even though few companies would admit that they have the problem, it is not unusual to meet people who have experienced the problem in their own passenger cars. Much of the knowledge concerning brake judder remains within the companies. Hence, very few people have the full picture. The purpose of the present paper is to give an overview of the brake judder problem.
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Kecsmar, J., and R. A. Shenoi. "Some Notes on the Influence of Manufacturing on the Fatigue Life of Welded Aluminum Marine Structures." Journal of Ship Production 20, no. 03 (August 1, 2004): 164–75. http://dx.doi.org/10.5957/jsp.2004.20.3.164.
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Designers are constantly looking for ways to reduce the structure weight to lower the overall displacement and hence the cost of fast ferries and other high-speed vessels. The easiest option for the designer is to choose a lightweight material. Aluminum has become the adopted choice of material for high-speed vessels owing to its high strength to weight characteristics. Unlike steel, aluminum is more prone to fatigue cracking and has no fatigue limit. In order to minimize weight, the designer will make use of finite element methods to optimize the scantlings and perform fatigue checks against established codes. This can lead to a structure that has the empirical margins of safety reduced owing to the accuracy of mathematical modeling. However, what is often overlooked is the effect the manufacturing process has on the fatigue life of the fabricated structure. This aspect is excluded from the designer's fatigue calculations, which assist in reducing the scantlings. Currently, there is no guidance for fatigue life reduction for the designer that establishes good and bad workshop practice, other than experience, or the implications of basic shipyard fabrication. It is shown that whereas strain-hardened alloys improve mechanical strength, they reduce ductility. This has consequences when forming the hull plate by potentially introducing crack like flaws into the alloy matrix if the plater overrolls the plate. If there is misalignment or there is too much gap between the plates, the weld will create localized stress concentrations. If the welder has poor joint preparation or gas shielding, porosity can be introduced into the weld. Porosity has a significant effect on the fatigue life of the weldment. This paper brings together a collection of data on such issues that the designer needs to be aware of to prevent an unwanted fatigue failure in the fabrication process.
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Krolo, Paulina, and Davor Grandić. "Hysteresis Envelope Model of Double Extended End-Plate Bolted Beam-to-Column Joint." Buildings 11, no. 11 (November 3, 2021): 517. http://dx.doi.org/10.3390/buildings11110517.
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In this study, a hysteresis envelope mathematical model for the double extended end-plate bolted beam-to-column joint is proposed. The aim of a proposed joint model is to provide a more realistic behaviour of steel frames under seismic loading by using nonlinear static pushover analysis. The hysteresis envelope model defines the ratios between the monotonic properties of the joints and the properties of the joints during cyclic deformation. The proposed models are based on the hysteresis curves of the joints obtained by numerical simulations. The numerical model takes into account the geometric nonlinearity of the connecting elements, preloading of bolts, contacts between plates and bolts, and nonlinear properties of steel. Nonlinear static pushover analyses of steel frames are performed where the behaviour of the joints is described using the proposed hysteresis envelope models. The results are compared with the nonlinear static pushover analyses of steel frames with a trilinear monotonic joint model. Based on the results, the values of maximum peak ground acceleration for moment-resisting frames with the monotonic model of joints and hysteresis envelope model are estimated.
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Wang, Wen, Wenjun Qiu, He Yang, Keqing Lu, Zhanfeng Chen, and Bingfeng Ju. "Error Analysis of a Spherical Capacitive Sensor for the Micro-Clearance Detection in Spherical Joints." Micromachines 11, no. 9 (September 3, 2020): 837. http://dx.doi.org/10.3390/mi11090837.
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Spherical joints have attracted increasing interest in the engineering applications of machine tools, industrial robots, medical equipment, and so on. As one of the promising methods of detecting the micro-clearance in spherical joints, the measurement accuracy of a spherical capacitive sensor could be affected by imperfectness during the manufacturing and installation of the sensor. This work presents error analysis of a spherical capacitive sensor with a differential structure and explores the dependence of the differential capacitance on manufacturing and the installation imperfectness. Five error sources are examined: the shape of the ball and the capacitive plate, the axial and radial offset of the plate, and the inclined installation of the plate. The mathematical models for calculating the capacitance errors of the spherical capacitive sensor are deduced and validated through a simulation using Ansoft Maxwell. The results show that the measurement accuracy of the spherical capacitive sensor is significantly affected by the shape of plates and ball, the axial offset, and the inclined angle of the plate. In contrast, the effect of the radial offset of the plate is quite small.
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Sauve´, R. G., and W. W. Teper. "Impact Simulation of Process Equipment Tubes and Support Plates—A Numerical Algorithm." Journal of Pressure Vessel Technology 109, no. 1 (February 1, 1987): 70–79. http://dx.doi.org/10.1115/1.3264858.
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The occurrence of flow-induced vibration fretting wear in process equipment such as heat exchangers and steam generators accounts for the majority of the failures due to vibration. One of the parameters which plays a vital role in the prediction of tube wear rate is the impact force which occurs when the free displacements of the tube exceed the clearance in the support plates, resulting in a collision. To date the determination of these impact forces reported in the literature has been restricted to simplified mathematical models which consider only straight spans of tube with gaps. The need to consider more generalized configurations has led to the development of an analytical method which simulates the nonlinear dynamic-impact response of multi-supported tubes including U-bends and the effect of nonuniform gap clearances at the supports. The approach is incorporated into a computer code based on the finite element and displacement methods using an unconditionally stable numerical integration scheme to solve the nonlinear equations of motion. The algorithm developed includes equilibrium iteration and variable time stepping based on convergence criteria, which ensures that temporal solution errors are minimized. The direct integration of the equations enables all the frequencies (subject to the finite element mesh) to be included. This is necessary since the high-frequency response at impacting may be significant. At present, the method is being used to simulate impact between tubes and support plates in steam generators and heat exchangers in order to determine tube bundle susceptibility to fretting wear failure at the design stage or operational phase. The paper describes the analytical development of the method, verification cases, and applications to the problem of tube/support plate impacting.
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de Lasa, Hugo. "The CREC Fluidized Riser Simulator a Unique Tool for Catalytic Process Development." Catalysts 12, no. 8 (August 12, 2022): 888. http://dx.doi.org/10.3390/catal12080888.
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The CREC Riser Simulator is a mini-fluidized bench scale unit invented and implemented in 1992, at the CREC (Chemical Reactor Engineering Centre), University of Western Ontario The CREC Riser Simulator can be operated at short reaction times, in the 3 s to 20 s range. The present review describes and evaluates the original basic concept of the 1992-CREC Riser Simulator Unit, and the improved design of the 2019-CREC Riser Simulator. Both the initial and the enhanced units are specially engineered to allow the rigorous assessment of both catalyst performance and catalytic reaction kinetics. Kinetic parameters of relatively simple and accurate mathematical models can be calculated using experimental data from the CREC Riser Simulator. Since its inception in 1992, the CREC Riser Simulator has been licensed to and manufactured for a significant number of universities and companies around the world. Several examples of scenarios where the CREC Riser Simulator can be employed to develop fluidized bed catalytic and heterogeneous reactor simulations are reported in this review. Among others, they include (a) hydrocarbon catalytic cracking, (b) the catalytic conversion of tar derived biomass chemical species, (c) steam and dry catalytic methane reforming, (d) the catalytic oxydehydrogenation of light paraffins, (e) the catalytic desulfurization of gasoline, and (f) biomass derived syngas combustion via chemical looping. In this review, special emphasis is given to the application of the CREC Riser Simulator to TIPB (tri-iso-propyl-benzene) catalytic cracking and the light paraffins catalytic oxydehydrogenation (PODH).
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Khan, Muhammad Sohail, Sun Mei, Shabnam, Unai Fernandez-Gamiz, Samad Noeiaghdam, and Aamir Khan. "Numerical Simulation of a Time-Dependent Electroviscous and Hybrid Nanofluid with Darcy-Forchheimer Effect between Squeezing Plates." Nanomaterials 12, no. 5 (March 6, 2022): 876. http://dx.doi.org/10.3390/nano12050876.
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In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid MoS2+Au/C2H6O2−H2O was formulated by dissolving the components of an inorganic substance such as molybdenum disulfide (MoS2) and gold (Au) in a base fluid of ethylene glycol/water. This hybrid non-liquid flow was modeled by various nonlinear mathematical fluid flow models and subsequently solved by numerical as well as analytical methods. For the numerical solution of nonlinear ODEs, a built-in function BVP4C was used in MATLAB, and the same problem was solved in MATHEMATICA by HAM. The result of the present problem related to the results obtained from the existing literature under certain conditions. The outcomes revealed that the concentration profiles were more sensitive to homogeneity diversity parameters. The simulation of the various physical parameters of the model indicated that the heat transfer through a mixture of hybrid nanofluids was greater than a simple nanofluid. In addition, the phenomenon of mixed convection was considered to improve the velocity of simple nanofluids and hybrid nanofluids, when both cases have low permeability. A rise in the volume fraction of the nanomaterials, Φ, was associated with an increase in the heat transfer rate. It was observed that the heat transfer rate of the hybrid nanofluids MoS2+Au/C2H6O2−H2O was higher than that of the single nanofluids MoS2/C2H6O2−H2O.
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Dodun, Oana, Laurențiu Slătineanu, Gheorghe Nagîț, Adelina Hrițuc, Andrei Marius Mihalache, and Irina Beșliu-Băncescu. "WEDM-Generated Slot Width Variation Modeling." Micromachines 13, no. 8 (July 31, 2022): 1231. http://dx.doi.org/10.3390/mi13081231.
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Wire electrical discharge machining (WEDM) is a process that is used when it is necessary to manufacture small-width slots with a micrometer accuracy or to precisely detach parts with complex contours from metal workpieces in the form of sheets or plates. The fact that the wire electrode rests only in the working zone in two of its guides allows it to achieve micrometric oscillations, leading to the generation of an error from the flat shape of the slot surfaces that gradually develops into the workpiece. The slot widths are influenced by several factors, such as the workpiece thickness, pulse-on time, pulse-off time, the wire tension force, the current, and the wire movement speed along its axis. Some theoretical assumptions about the behavior of the wire electrode were first considered. An experimental research plan was then designed to obtain additional information on the influence of the mentioned factors on the slot width in different positions of the cross-section through the slot. The statistical processing of the experimental results led to the elaboration of empirical mathematical models that highlight the order of influence and the intensity of the influence exerted by the factors mentioned above.
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Sreeraj, P., T. Kannan, and Subhashis Maji. "Optimization of GMAW Process Parameters Using Particle Swarm Optimization." ISRN Metallurgy 2013 (January 22, 2013): 1–10. http://dx.doi.org/10.1155/2013/460651.
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To improve the corrosion-resistant properties of carbon steel cladding process is usually used. It is a process of depositing a thick layer of corrosion resistant material-over carbon steel plate. Most of the engineering applications require high strength and corrosion resistant materials for long-term reliability and performance. By cladding, these properties can be achieved with minimum cost. The main problem faced in cladding is the selection of optimum combinations of process parameters for achieving quality clad and hence good clad bead geometry. This paper highlights an experimental study to optimize various input process parameters (welding current, welding speed, gun angle, contact tip to work distance, and pinch) to get optimum dilution in stainless steel cladding of low-carbon structural steel plates using gas metal arc welding (GMAW). Experiments were conducted based on central composite rotatable design with full-replication technique and mathematical models were developed using multiple regression method. The developed models have been checked for adequacy and significance. Using particle swarm optimization (PSO) the parameters were optimized to get minimal dilution.
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Yi, Sang-ri, and Junho Song. "Particle Filter Based Monitoring and Prediction of Spatiotemporal Corrosion Using Successive Measurements of Structural Responses." Sensors 18, no. 11 (November 13, 2018): 3909. http://dx.doi.org/10.3390/s18113909.
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Prediction of structural deterioration is a challenging task due to various uncertainties and temporal changes in the environmental conditions, measurement noises as well as errors of mathematical models used for predicting the deterioration progress. Monitoring of deterioration progress is also challenging even with successive measurements, especially when only indirect measurements such as structural responses are available. Recent developments of Bayesian filters and Bayesian inversion methods make it possible to address these challenges through probabilistic assimilation of successive measurement data and deterioration progress models. To this end, this paper proposes a new framework to monitor and predict the spatiotemporal progress of structural deterioration using successive, indirect and noisy measurements. The framework adopts particle filter for the purpose of real-time monitoring and prediction of corrosion states and probabilistic inference of uncertain and/or time-varying parameters in the corrosion progress model. In order to infer deterioration states from sparse indirect inspection data, for example structural responses at sensor locations, a Bayesian inversion method is integrated with the particle filter. The dimension of a continuous domain is reduced by the use of basis functions of truncated Karhunen-Loève expansion. The proposed framework is demonstrated and successfully tested by numerical experiments of reinforcement bar and steel plates subject to corrosion.
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Melyukov, Valery, and Evgeny A. Marinin. "Controlled Process of Crystallization in Weld Pool." Materials Science Forum 1037 (July 6, 2021): 258–63. http://dx.doi.org/10.4028/www.scientific.net/msf.1037.258.
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In this report the problem of control of solidification crack formation in welded plates is considered. In this problem the welding source is determined in dependence on the preset configuration and curvature of the rear part weld pool. A double ellipsoid model of weld pool with preset semi-axes may be used for the first approximation of preset weld pool configuration. It is an inverse problem which may be more efficiently solved as optimal control problem. The Function of welding source as a controlling function obtained in the result of solution is determined in a class of piecewise continuous functions which is more common class and the continuous-smooth functions are special partial case of common class. Recent methods of optimal control which use for solution of optimal control problems require to present the controlling functions in class of piecewise constant functions. Laser influence, electron beam, plasma, arc and submerged arc are the welding sources with high concentrated energy. A mathematical models of these welding sources may be introduced in class of piecewise continuous function with an efficient accuracy.
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Sreeraj, P., T. Kannan, and Subhashis Maji. "Estimation of Optimum Dilution in the GMAW Process Using Integrated ANN-GA." Journal of Engineering 2013 (2013): 1–17. http://dx.doi.org/10.1155/2013/285030.
Full textAbstract:
To improve the corrosion resistant properties of carbon steel, usually cladding process is used. It is a process of depositing a thick layer of corrosion resistant material over carbon steel plate. Most of the engineering applications require high strength and corrosion resistant materials for long-term reliability and performance. By cladding these properties can be achieved with minimum cost. The main problem faced on cladding is the selection of optimum combinations of process parameters for achieving quality clad and hence good clad bead geometry. This paper highlights an experimental study to optimize various input process parameters (welding current, welding speed, gun angle, and contact tip to work distance and pinch) to get optimum dilution in stainless steel cladding of low carbon structural steel plates using gas metal arc welding (GMAW). Experiments were conducted based on central composite rotatable design with full replication technique, and mathematical models were developed using multiple regression method. The developed models have been checked for adequacy and significance. In this study, artificial neural network (ANN) and genetic algorithm (GA) techniques were integrated and labeled as integrated ANN-GA to estimate optimal process parameters in GMAW to get optimum dilution.
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Al-Ma’aiteh, Tareq I., and Oliver Krammer. "Non-Newtonian numerical modelling of solder paste viscosity measurement." Soldering & Surface Mount Technology 31, no. 3 (June 3, 2019): 176–80. http://dx.doi.org/10.1108/ssmt-11-2018-0044.
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PurposeThe purpose of this paper is to present the establishment of a computational fluid dynamics model for investigating different non-Newtonian rheological models of solder pastes by simulating solder paste viscosity measurement. A combined material model was established which can follow the measured, apparent viscosity values with lower error.Design/methodology/approachThe model included a parallel plate arrangement of rheometers. The diameter of the plate was 50 mm, whereas the gap between the plates was 0.5 mm. Only one quarter of the plate was modelled to enable using fine enough mesh, while keeping the calculation time low. Non-Newtonian properties were set using user defined function in Ansys, based on the Cross and Carreau–Yasuda material models. The viscosity values predicted by the mathematical models were compared to measured viscosity values of different types of solder pastes.FindingsIt was found that the Cross model predicts the apparent viscosity with a relatively high error (even approximately 50 per cent) at lower shear rates, whereas the Carerau–Yasuda model has higher errors at higher shear rates. The application of the proposed, combined model can result in a much lower error in the apparent viscosity between the calculated and measured viscosity values.Originality/valueThe error of Cross and Carreau–Yasuda material models has not been investigated yet in details. The proposed, combined material model can be applied for subsequent simulations via the described UDF, e.g. in the numerical modelling of the stencil printing. This can result in a more accurate modelling of the stencil printing process, which is inevitable considering the printing of solder paste for today fine-pitch, small size components.
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Zou, Guang, Kian Banisoleiman, and Arturo González. "Bayesian maintenance decision optimisation based on computing the information value from condition inspections." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 235, no. 4 (March 26, 2021): 545–55. http://dx.doi.org/10.1177/1748006x20978127.
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A challenge in marine and offshore engineering is structural integrity management (SIM) of assets such as ships, offshore structures, mooring systems, etc. Due to harsh marine environments, fatigue cracking and corrosion present persistent threats to structural integrity. SIM for such assets is complicated because of a very large number of rewelded plates and joints, for which condition inspections and maintenance are difficult and expensive tasks. Marine SIM needs to take into account uncertainty in material properties, loading characteristics, fatigue models, detection capacities of inspection methods, etc. Optimising inspection and maintenance strategies under uncertainty is therefore vital for effective SIM and cost reductions. This paper proposes a value of information (VoI) computation and Bayesian decision optimisation (BDO) approach to optimal maintenance planning of typical fatigue-prone structural systems under uncertainty. It is shown that the approach can yield optimal maintenance strategies reliably in various maintenance decision making problems or contexts, which are characterized by different cost ratios. It is also shown that there are decision making contexts where inspection information doesn’t add value, and condition based maintenance (CBM) is not cost-effective. The CBM strategy is optimal only in the decision making contexts where VoI > 0. The proposed approach overcomes the limitation of CBM strategy and highlights the importance of VoI computation (to confirm VoI > 0) before adopting inspections and CBM.
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Zelenyak, Volodymyr, Myroslava Klapchuk, Lubov Kolyasa, Oksana Oryshchyn, and Svitlana Vozna. "Determining patterns in thermoelastic interaction between a crack and a curvilinear inclusion located in a circular plate." Eastern-European Journal of Enterprise Technologies 6, no. 7 (114) (December 21, 2021): 52–58. http://dx.doi.org/10.15587/1729-4061.2021.243990.
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A two-dimensional mathematical model of the thermoelastic state has been built for a circular plate containing a curvilinear inclusion and a crack, under the action of a uniformly distributed temperature across the entire piece-homogeneous plate. Using the apparatus of singular integral equations (SIEs), the problem was reduced to a system of two singular integral equations of the first and second kind on the contours of the crack and inclusion, respectively. Numerical solutions to the system of integral equations have been obtained for certain cases of the circular disk with an elliptical inclusion and a crack in the disk outside the inclusion, as well as within the inclusion. These solutions were applied to determine the stress intensity coefficients (SICs) at the tops of the crack. Stress intensity coefficients could later be used to determine the critical temperature values in the disk at which a crack begins to grow. Therefore, such a model reflects, to some extent, the destruction mechanism of the elements of those engineering structures with cracks that are operated in the thermal power industry and, therefore, is relevant. Graphic dependences of stress intensity coefficients on the shape of an inclusion have been built, as well as on its mechanical and thermal-physical characteristics, and a distance to the crack. This would make it possible to analyze the intensity of stresses in the neighborhood of the crack vertices, depending on geometric and mechanical factors. The study's specific results, given in the form of plots, could prove useful in the development of rational modes of operation of structural elements in the form of circular plates with an inclusion hosting a crack. The reported mathematical model builds on the earlier models of two-dimensional stationary problems of thermal conductivity and thermoelasticity for piece-homogeneous bodies with cracks.
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Abejide, Samuel, Mohamed M. H. Mostafa, Dillip Das, Bankole Awuzie, and Mujib Rahman. "Pavement Quality Index Rating Strategy Using Fracture Energy Analysis for Implementing Smart Road Infrastructure." Sensors 21, no. 12 (June 20, 2021): 4231. http://dx.doi.org/10.3390/s21124231.
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Developing a responsive pavement-management infrastructure system is of paramount importance, accentuated by the quest for sustainability through adoption of the Road Traffic Management System. Technological advances have been witnessed in developed countries concerning the development of smart, sustainable transportation infrastructure. However, the same cannot be said of developing countries. In this study, the development of a pavement management system at network level was examined to contribute towards a framework for evaluating a Pavement Quality Index and service life capacity. Environmental surface response models in the form of temperature and moisture variations within the pavement were applied, using sensor devices connected to a data cloud system to carry out mathematical analysis using a distinctive mesh analysis deformation model. The results indicated variation in the Resilient Modulus of the pavement, with increasing moisture content. Increase in moisture propagation increased saturation of the unbound granular base which reduced the elastic modulus of the sub-base and base layer and reduced the strength of the pavement, resulting in bottom-up cracks and cracking failure. The horizontal deformation reduced, indicating that the material was experiencing work hardening and further stress would not result in significant damage. Increasing temperature gradient resulted in reduced stiffness of the asphalt layer. In tropical regions, this can result in rutting failure which, over time, results in top-down cracks and potholes, coupled with increasing moisture content.