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Статті в журналах з теми "Rate-dependent strength behaviour"
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Pathan, Mehtab V., Borja Erice, Sathiskumar A. Ponnusami, and Nik Petrinic. "Experimental characterisation of rate-dependent compression behaviour of fibre reinforced composites." EPJ Web of Conferences 183 (2018): 02053. http://dx.doi.org/10.1051/epjconf/201818302053.
Повний текст джерелаАнотація:
Fibre reinforced polymers (FRP) materials are being increasingly used for aerospace and automotive structural applications. One of the critical loading conditions for such applications is impact, consequently, understanding of the composite behavior under such loads becomes critical for structural design. The analysis and design process for achieving impact-resistant composite structures requires rate-dependent constitutive models, which, in turn, requires material properties of the composite over a range of strain rates. It is, therefore, the objective of the research to investigate the strain rate-dependent behavior of fiber reinforced composites under compressive loads for a wide range of fiber orientations. Quasi-static (≈ 1e-3 s−1) and high loading (≈ 200 s−1) rates are considered for the experimental study. Accordingly, two different test setups are utilized, a screw-driven universal testing machine for quasi-static tests and a Split Hopkinson Pressure Bar (SHPB) system for dynamic tests. The stress-strain response of the composite is reported for the different fiber orientations and the strain rates, revealing the rate-dependent characteristics of the carbon fiber reinforced composite. From the test results, it is observed that, the dependency of the fracture strength on the loading rate is significant. The results are summarised in terms of the failure envelope in the transverse compression-in-plane shear σ22 − σ12 plane for the two strain rates.
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Deshpande, V. M., and T. Chakraborty. "Dynamic compressive behaviour of Rewa shale through SHPB tests." IOP Conference Series: Earth and Environmental Science 1124, no. 1 (January 1, 2023): 012042. http://dx.doi.org/10.1088/1755-1315/1124/1/012042.
Повний текст джерелаАнотація:
Abstract The present work investigates the high strain rate behaviour of transversely isotropic Rewa shale using a split Hopkinson pressure bar. Rewa shale, a type of Vindhyan shale, is collected from Rewa district in the Madhya Pradesh state of India. Samples are loaded at various strain rates ranging from 110/s to 874/s. It is found that the compressive strength is rate-dependent, and it increases as the strain rate rises. The highest compressive strength is exhibited by samples at 0° and 90°. Samples at 30°, 45° and 60° fail at higher strains and strain rates. All samples subjected to dynamic compressive loading are pervasively fragmented. The results can potentially be applied to improve drilling and blasting operations.
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Takiguchi, M., S. Izumi, and F. Yoshida. "Rate-dependent shear deformation of ductile acrylic adhesive and its constitutive modelling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 6 (June 2004): 623–29. http://dx.doi.org/10.1243/095440604774202268.
Повний текст джерелаАнотація:
Recently, new types of structural adhesive with high ductility, as well as high strength, have been developed and put on the market. Such high ductile adhesives usually have strong rate sensitivity in their flow stress. In order to investigate the rate-dependent deformation behaviour of an acrylic adhesive, tensile lap shear tests were performed at various crosshead speeds at room temperature. Stress relaxation tests were also performed. In the tensile lap shear tests, it was found that the shear flow stress of the adhesive resin increased remarkably with increasing shearing speed. In the stress relaxation tests, the stress decreased rapidly at the early stage, and it gradually approached an asymptotic stress value. In order to describe such rate-dependent deformation characteristics of adhesive resin, a viscoplastic constitutive model is presented in this paper. The shear stress-strain responses, as well as stress relaxation behaviour, predicted by the present model agree well with the corresponding experimental results.
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Çelen, S., and K. Kahveci. "Microwave drying behaviour of tomato slices." Czech Journal of Food Sciences 31, No. 2 (April 18, 2013): 132–38. http://dx.doi.org/10.17221/30/2012-cjfs.
Повний текст джерелаАнотація:
The microwave drying behaviour of tomato slices was investigated experimentally to determine the effects of microwave power on the drying rate, energy consumption, and dried product quality in terms of colour, and a theoretical model was proposed to define the drying curves of tomato slices. The experiments performed with the microwave power of 90, 180, 360, and 600 W indicate that the drying time and the energy consumption decreased considerably with an increase in microwave power. The experiments also revealed that the drying rate shows first an increase and then a decrease during drying, and that the colour quality of the product deteriorates significantly with the increase of the microwave power. A theoretical model was developed using the solution of energy equation considering the microwave power as an internal heat source. The electric field strength inside the material was assumed to be dependent on the moisture content and the constants emerging from this assumption were obtained by minimising the sum of squared differences between the theoretical results and experimental data obtained for various drying conditions. The results show that the values proposed for the constants provide a good agreement between the theoretical and experimental drying behaviour.
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Maqsood, Zain, Junichi Koseki, and Hiroyuki Kyokawa. "Effects of loading rate on strength and deformation characteristics of gypsum mixed sand." E3S Web of Conferences 92 (2019): 05008. http://dx.doi.org/10.1051/e3sconf/20199205008.
Повний текст джерелаАнотація:
It has been unanimously acknowledged that the strength and deformation characteristics of bounded geomaterials, viz. cemented soils and natural rocks, are predominantly governed by the rate of loading/deformation. Rational evaluation of these time-dependent characteristics due to viscosity and ageing are vital for the reliable constitutive modelling. In order to study the effects of ageing and loading/strain rate (viscosity) on the behaviour of bounded geomaterials, a number of unconfined monotonic loading tests were performed on Gypsum Mixed Sand (GMS) specimens at a wide range of axial strain rates; ranging from 1.9E-05 to 5.3E+00 %/min (27,000 folds), and at different curing periods. The results indicate shifts in the viscous behaviour of GMS at critical strain rates of 2.0E-03 and 5.0E-01 %/min. In the light of this finding, the results are categorized into three discrete zones of strain rates, and the behaviour of GMS in each of these zones is discussed. A significant dependency of peak strength and stress-strain responses on strain rate was witnessed for specimens subjected to strain rates lesser than 2.0E-03 %/min, and the effects of viscosity/strain rate was found to be insignificant at strain rate higher than 5.0E-01%/min.
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Kim, Jang-Kyo, Man-Lung Sham, Min-Seok Sohn, and Shisheng Hu. "Effects of Fibre Surface Treatment on Dynamic Tensile Properties of Glass Woven Fabric Reinforced Vinylester Composites." Polymers and Polymer Composites 13, no. 5 (July 2005): 453–66. http://dx.doi.org/10.1177/096739110501300503.
Повний текст джерелаАнотація:
Glass fibre has been recognized as a strain rate dependent material. Its failure behaviour changes from brittle to ductile as the strain rate increases. As a consequence, the strength of the glass fibre increases, but the fibres within a composite become more prone to debond from the matrix because of the brittleness of the matrix material, promoted by the high strain rate. In the present study, the tensile responses of glass woven fabric reinforced vinyl ester composites with various fibre surface treatments are examined under static and dynamic loading conditions. The results show that both the ductility and the strength of the composites increased with increasing strain rate. The tensile strength was lower and the failure strain was higher in the weft direction than in the warp direction, because of excessive crimping in the former direction. The tensile strength in general increased with increasing silane concentration, for the majority of strain rates studied. The influence of fibre surface treatment on the impact tensile strength and modulus of composites were functionally similar, confirming the influence of fibre-matrix interphase properties on composite fracture behaviour at high strain rates.
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Nashed, Nour, Stephanie Chan, Matthew Lam, Taravat Ghafourian, and Ali Nokhodchi. "Effect of pH, Ionic Strength and Agitation Rate on Dissolution Behaviour of 3D-Printed Tablets, Tablets Prepared from Ground Hot-Melt Extruded Filaments and Physical Mixtures." Biomedicines 11, no. 2 (January 27, 2023): 375. http://dx.doi.org/10.3390/biomedicines11020375.
Повний текст джерелаАнотація:
With the current focus on 3D-printing technologies, it is essential to understand the processes involved in such printing methods and approaches to minimize the variability in dissolution behaviour to achieve better quality control outcomes. For this purpose, two formulations of theophylline tablets were prepared using hydroxypropyl cellulose (HPC) and ethyl cellulose (EC). Among the two types of tablets, three different methods (physical mixture (PM), hot-melt extrusion (HME) and 3D-printing fused deposition modelling (FDM)) were applied and their dissolution behaviours were studied under various conditions using a biodissolution tester. This was carried out at pH values of 1.2, 2.2, 5.8, 6.8, 7.2 and 7.5, mimicking the medium in the gastrointestinal tract. Dissolution tests under two dipping rates (10 dpm and 20 dpm) and two ionic strengths (0.2 M and 0.4 M) were conducted to mimic fed and fasting conditions. The dissolution efficiency (DE%), release rate, similarity factor (f2) and difference factor (f1) were calculated. When comparing the DE%, the formulation containing EC showed less sensitivity to changes in the dipping rate and ionic strength compared to the HPC formulation. As for the manufacturing method, 3D-printing FDM could improve the robustness of the dissolution behaviour of both formulations to dipping rate changes. However, for ionic strength changes, the effect of the manufacturing method was dependent on the formulation composition. For example, the 3D-printed tablets of the HPC formulation were more sensitive to changes in ionic strength compared to the EC-containing formulation. The release mechanism also changed after the thermal process, where n values in the Korsmeyer–Peppas model were much higher in the printing and HME methods compared to the PM. Based on the formulation composition, the 3D-printing method could be a good candidate method for tablets with a robust dissolution behaviour in the GI tract. Compared to HPC polymers, using hydrophobic EC polymers in printable formulations can result in a more robust dissolution behaviour in fed and fasting states.
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Li, Xueyang, Christian C. Roth, and Dirk Mohr. "Large Deformation Behavior of High Strength Steel Under Extreme Loading Conditions: High Temperature and High Strain Rate Experiments and Modeling." EPJ Web of Conferences 183 (2018): 01053. http://dx.doi.org/10.1051/epjconf/201818301053.
Повний текст джерелаАнотація:
Plasticity and fracture experiments are carried out on flat smooth and notched tensile specimens extracted from DP800 steel sheets. A split Hopkinson pressure bar testing system equipped with a load inversion device is utilized to reach high strain rates. Temperature dependent experiments ranging from 20°C to 300°C are performed at quasi-static strain rates. The material exposes a monotonic strain hardening behaviour with a non-monotonic temperature dependency. The rate-independent material behaviour at room-temperature is described with a non-associated Hill’48 plasticity model and an Swift-Voce strain hardening. A machine learning based model is used multiplicatively to capture the rate and temperature responses. A good agreement between measured and simulated force-displacement curves as well as local surface is obtained. The loading paths to fracture are then extracted to facilitate further development of a temperature dependent fracture initiation model.
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Yin, Jian-Hua, and James Graham. "Elastic viscoplastic modelling of the time-dependent stress-strain behaviour of soils." Canadian Geotechnical Journal 36, no. 4 (November 22, 1999): 736–45. http://dx.doi.org/10.1139/t99-042.
Повний текст джерелаАнотація:
This paper presents a new framework for elastic viscoplastic (EVP) constitutive modelling. In developing the model, a general one-dimensional elastic viscoplastic (1D EVP) relationship is first derived for isotropic stressing conditions using an "equivalent-time" concept. This 1D EVP model is then generalized into a three-dimensional EVP model based on Modified Cam-Clay and viscoplasticity. Fitting functions are proposed for fitting data when model parameters are being determined. Using these functions, a specific EVP model is developed which describes the time-dependent stress-strain behaviour of soils under triaxial stress states. This model has been calibrated using data from a densely compacted sand-bentonite mixture. The calibrated model is used to compute time-dependent (or strain rate dependent) stress-strain curves from a multistage shear creep test and a step-changed, constant strain rate undrained triaxial compression test. Predictions from the EVP model are in general agreement with measured values. It is demonstrated that the model can simulate accelerating creep when deviator stresses are close to the shear strength envelope in a q creep test. It can also model the behaviour in unloading-reloading and relaxation. Limitations and possible improvements are also indicated.Key words: equivalent time, stress-strain, time dependent, elastic, viscoplastic, triaxial.
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Banerjee, Amborish, B. Gangadhara Prusty, and Saroj Bhattacharyya. "Rate-dependent mechanical strength and flow behaviour of dual-phase high carbon steel at elevated temperatures: An experimental investigation." Materials Science and Engineering: A 744 (January 2019): 224–34. http://dx.doi.org/10.1016/j.msea.2018.12.002.
Повний текст джерелаДисертації з теми "Rate-dependent strength behaviour"
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Tiwari, Gaurav. "Strain-rate Dependence of Rock Joint Strength and Related Stability of Slopes and Tunnels." Thesis, 2018. http://etd.iisc.ac.in/handle/2005/4192.
Повний текст джерелаАнотація:
Understanding the strain rate-dependent strength behavior of rock joints is important since displacement rates along rock joints in field can exceed the suggested displacement rates (0.02 mm/min-0.5 mm/min) for laboratory tests, in the events of thermal loads, excavations and seismic vibrations. Quantification of strain rate dependency of rock joint strength is not available in literature and presently there is no method, which considers the effect of rate-dependent strength behaviour of rock joints in the stability analysis of slopes and tunnels.
The objective of this thesis is to investigate the effects of displacement rate on the shear strength behaviour of rock joints and quantify the rate dependent shear strength of rock joints. To achieve this, triaxial compression tests were carried out on model jointed rock specimens of irregular rough joints at varying rock densities, confining stresses and pre-loading histories. Indentation creep experiments were carried out to substantiate the postulates from triaxial compression tests. Based on these tests and from the database of experiments on rate dependent strength of jointed rocks compiled from literature, a probabilistic approach, which can consider the effect of displacement rate along rock joints in the estimation of shear strength of rock joints, is developed. Applicability of this approach for the stability analysis of slopes and tunnels against structurally-controlled failures is demonstrated through case studies of a large slope and three different tunnels. For the stability analysis against stress controlled failure, a GSI (Geological Strength Index) based quantitative approach is proposed, which can be used to quantify the uncertainty in residual strength parameters along with peak strength parameters of the rock mass.
Results from the experiments and probabilistic analyses highlight the importance of considering displacement rate effect while estimating the strength of rock joints. Triaxial compression tests on rock joints have shown that the rate dependency of rock joint strength is influenced by the density, confining stress and pre-loading history of rock joints. Stability analyses of slope and tunnels showed that ignoring the rate dependency of strength results in serious errors in the estimation of probability of failure and reliability index and further in the estimation of support requirements
Книги з теми "Rate-dependent strength behaviour"
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Tandanand, Sathit. Time-dependent behavior of coal measure rocks: Adsorption rate and strength degradation. Avondale, Md: U.S. Dept. of the Interior, Bureau of Mines, 1987.
Знайти повний текст джерелаЧастини книг з теми "Rate-dependent strength behaviour"
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Armstrong, Ronald W. "Hall–Petch Relationship in Aluminum and Aluminum Alloys." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000234.
Повний текст джерелаАнотація:
The mechanical properties of aluminum are shown to be of special importance beginning from the early 20th-century production of the material in single crystal and polycrystalline form. Experimental and theoretical researches of the time were concerned with particular influence of polycrystalline microstructure and the presence of crystal (grain) boundaries on both the material strength properties and on relation of those same properties to those for the full range of metal and alloy structures. Now it is well established that a relatively low value of the microstructural stress intensity, kε, is obtained for aluminum in the generalized Hall–Petch relation for its stress–strain, σε − ε, behavior depending on the average grain diameter, l, with intercept (friction) stress, σ0ε, which relation is given as: id="unequ63_1">σε=σ0ε+kεl−1/2With hindsight, taking σε = σ0ε provided the first connection between single crystal and polycrystalline strength measurements in the pioneering Taylor theory of plasticity proposed for aluminum and other face-centered cubic metals. Later, conventional and ultrafine grain size measurements are shown to verify the fuller H–P dependence. The present account builds onto the early history. A description is given for temperature, strain rate, and alloy-dependent mechanical property measurements. An understanding of the total measurements is described in terms of a dislocation pile-up model description for the relation. Emphasis is given to kε for pure aluminum and related metals being determined by cross-slip forced at grain boundaries. Particular attention is given to two characteristics of the metal mechanical behavior: (1) very high rate loading deformations leading to shock and shock-less isentropic compression experiments and (2) important grain size influences on nanopolycrystalline material behaviors. Additional results are presented on H–P aspects of the material strain ageing, shear banding, ductile fracturing, and fatigue behaviors.
Тези доповідей конференцій з теми "Rate-dependent strength behaviour"
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Natori, K., R. Kishi, H. Shimahara, Y. Arao, and T. Tanaka. "Effect of mesostructure on strain rate dependent behaviour in high strength steel sheets." In HPSM/OPTI 2014. Southampton, UK: WIT Press, 2014. http://dx.doi.org/10.2495/hpsm140141.
Повний текст джерела
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Lee, Shi-Wei Ricky, and Lan Hong Dai. "Characterization of Strain Rate-Dependent Behavior of 63Sn-37Pb Solder Using Split Hopkinson Torsional Bars (SHTB)." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/epp-24730.
Повний текст джерелаАнотація:
Abstract The present study is aimed at the experimental characterization of strain-rate dependent behaviour of solder materials under impulsive shear loading. In order to achieve this objective, a unique testing technique, namely, split Hopkinson torsion bar (SHTB) is employed. The solder material under investigation is 63Sn-37Pb. The experimental results indicate that the shear behavior of the solder joint is very sensitive to the strain rate and the dynamic shear strength of the solder joint is much higher than the static one.
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Natali, Arturo N., Emanuele L. Carniel, Piero G. Pavan, Alessio Gasparetto, Franz G. Sander, Christina Dorow, and Martin Geiger. "Constitutive Formulation for Numerical Analysis of Visco-Hyperelastic Damage Phenomena in Soft Biological Tissues." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95254.
Повний текст джерелаАнотація:
Soft biological tissues show a strongly non linear and time-dependent mechanical response and undergo large strains under physiological loads. The microstructural arrangement determines specific anisotropic macroscopic properties that must be considered within a constitutive formulation. The characterization of the mechanical behaviour of soft tissues entails the definition of constitutive models capable of accounting for geometric and material non linearity. In the model presented here a hyperelastic anisotropic formulation is adopted as the basis for the development of constitutive models for soft tissues and can be properly arranged for the investigation of viscous and damage phenomena as well to interpret significant aspects pertaining to ordinary and degenerative conditions. Visco-hyperelastic models are used to analyze the time-dependent mechanical response, while elasto-damage models account for the stiffness and strength decrease that can develop under significant loading or degenerative conditions. Experimental testing points out that damage response is affected by the strain rate associated with loading, showing a decrease in the damage limits as the strain rate increases. This phenomena can be investigated by means of a model capable of accounting for damage phenomena in relation to viscous effects. The visco-hyperelastic damage model developed is defined on the basis of a Helmholtz free energy function depending on the strain-damage history. In particular, a specific damage criterion is formulated in order to evaluate the influence of the strain rate on damage. The model can be implemented in a general purpose finite element code. This makes it possible to perform numerical analyses of the mechanical response considering time-dependent effects and damage phenomena. The experimental tests develop investigated tissue response for different strain rate conditions, accounting for stretch situations capable of inducing damage phenomena. The reliability of the formulation is evaluated by a comparison with the results of experimental tests performed on pig periodontal ligament.
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Schulz, Michael. "On the Creep Rupture Prediction of Composite Pressure Vessels." In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-26034.
Повний текст джерелаАнотація:
This article illustrates a concept of predicting the time dependent deformation and creep rupture strength of carbon fibre reinforced plastics (CFRP). In the presented concept the viscoelastic behaviour of the resin is determined by creep rupture tests at different temperature and load levels. Out of the experiments the relaxation spectrum of the resin is modelled including the spread. With the help of the classical rule of mixture and a modified classical laminate theory the minimum strain rate for the composite will be determined. The results will be compared to experimental data. Furthermore the Monkman-Grant approach is used to determine the time-to-failure strain-rate relation. Therefore an elastic solution of the classical laminate theory is used including Puck’s failure criteria to compute the Monkman-Grant relation. A Monte Carlo Simulation will be done to include the spread of the Monkman-Grant relation. The results will be compared to experimental results of unidirectional specimens. Finally it will be explained how the lifetime of a pressure vessel can be computed using the explained concept.
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Dutta, Sujan, Bipul Hawlader, Ryan Phillips, and Mike Paulin. "Numerical Investigation of Vertical Penetration of Steel Catenary Riser Near the Touch Down Zone." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64608.
Повний текст джерелаАнотація:
Steel catenary risers (SCR) are widely used in offshore to transport hydrocarbon from the seabed to floating or fixed platforms. The fatigue life of SCR near the touchdown zone (TDZ) is one of the main design concerns because the risers are often subjected to cyclic loading (vertical penetration/uplift, lateral and axial displacements) from various sources of environmental loadings, such as sea waves and currents. Numerical modeling of the penetration and uplift behaviour of an SCR is a challenging task. Most of the models available in the literature for uplift resistance are empirical, which have been developed mainly from the results of physical experiments. In this study, numerical simulation of vertical resistance is presented. Analysis is performed using ANSYS CFX software. Strain-softening and strain-rate dependent undrained shear strength behavior of soft clay sediment has been reported by many researchers. Unfortunately, these models were not available in CFX. Numerical simulations presented in this paper are performed implementing this behavior in CFX. Numerical results are compared with available empirical models. The present CFX modeling explains some mechanisms involved in trench formation and suction development during uplift. Factors affecting uplift resistance such as the size and shape of the trench are also discussed from a parametric study.
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Pokutylowicz, Norman, Michael J. Luton, Ruzica A. Petkovic, Jim A. Nemes, and Steve Yue. "Simulation of Dynamic Ductile Failure in Pipelines." In 2000 3rd International Pipeline Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/ipc2000-134.
Повний текст джерелаАнотація:
A finite-element method computer simulation was constructed in order to assist in determining what material properties affect the resistance to dynamic ductile failure in pipelines. Such failure is caused by stable axial tearing that involves a substantial amount of plastic deformation, and is driven by the kinetic energy of the expanding gas. Various semi-empirical relationships exist in the literature to predict the toughness required for resistance to the propagation of a dynamic ductile failure, but these tend to be ineffective when applied to higher strength grades of steel. The present finite-element model is composed of two main sub-models. The gas decompression algorithm is based on analytical expressions and calculates the gas pressure throughout the pipe as the ductile fracture propagates. The material-response algorithm determines the behaviour of the material under the changing loading conditions. It simulates the material response, including rate-dependent yield as well as anisotropy of yield and work hardening. The model is validated by using comparisons with published data from the literature. This paper focuses on a description of the different components of the model and their interaction. In addition some observations from the various simulations are discussed.
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HIGUCHI, RYO, SOTA OSHIMA, SHU MINAKUCHI, TOMOHIRO YOKOZEKI, and TAKAHIRA AOKI. "STUDY ON COOLING RATE-DEPENDENT MECHANICAL PROPERTIES OF THERMOPLASTIC COMPOSITES." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35841.
Повний текст джерелаАнотація:
This study investigates the effect of solidification conditions on the crystallization behaviors and mechanical properties of thermoplastic resin and carbon fiber reinforced thermoplastics (CFRTP). In particular, the crystallinity, elastic modulus, plastic behavior, strength, and fracture toughness were investigated in Polyphenylene Sulfide (PPS) and CF/PPS manufactured by different cooling rates. Based on experimental results, the cooling-rate-dependent elasto-plastic constitutive law of resin was developed empirically. Finally, the homogenized simulations of CF/PPS were conducted using the developed empirical model, and predicted results were compared with experiments.
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Chang, Le, Changyu Zhou, and Xiaohua He. "Room Temperature Creep Behavior and its Effect on Tensile Properties of CP-Ti." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65129.
Повний текст джерелаАнотація:
Commercial pure titanium (CP-Ti) is an attractive material, due to its good properties such as high strength, high specific work hardening ability, excellent plasticity, toughness, corrosion resistance and weld ability. It is commonly used in pressure vessels, such as heat exchangers, pumps, valves and so on. It has been reported that the room temperature creep has a great influence on the failure of titanium pressure vessel. In this paper, in order to investigate room temperature creep behavior and its effect on tensile properties of CP-Ti, both creep and tensile experiments were carried out. According to creep experiment results, CP-Ti shows strong stress dependent creep behavior at the creep stress higher than 305MPa. On the contrary, the strong loading rate dependent creep behavior occurs at the creep stress lower than 305MPa. Besides, creep strain of CP-Ti can be reduced by pretension. As pretension reaches 6%, creep behavior of CP-Ti is completely suppressed at the creep stress of 320MPa. Subsequent tensile test results show that the occurrence of room temperature creep obviously enhances the strength of CP-Ti. With the increase of creep strain and loading rate in previous creep tests, the yield strength and tensile strength of CP-Ti increase.
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Zhou, Binbin, Changyu Zhou, and Xiaohua He. "Study on Fatigue Crack Growth Behavior of Zr702/TA2/Q345R Composite Plate With a Through-Wall Crack and a Crack Normal to Interface for SENT Specimen." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93325.
Повний текст джерелаАнотація:
Abstract In this paper, the fatigue crack growth behavior of Zr702/TA2/Q345R composite plate with a through-wall crack and a crack normal to interface for SENT specimen are studied. For the through-wall crack, the mutual interference in fatigue crack growth rate is found. The crack growth rate of the through-wall crack on both sides in Zr702/TA2/Q345R composite plate depends on the difference of stress intensity factors amplitude caused by the different positions of crack tips on both sides and the crack growth rate in corresponding homogeneous material. For the crack normal to interface, two crack propagation directions are taken into account. When crack initiates from the lower strength material side, the crack growth rate decreases to the minimum before crack penetrates the interface. After crack penetrates the interface, crack growth rate accelerates continuously. When crack initiates from the higher strength material side, the fatigue crack growth rate generally increases with the crack length. For both crack forms, all experiment results demonstrate that the crack growth rate is dependent on the competition of the stress intensity factor amplitude, the crack growth rate in corresponding homogeneous material and the interface strength. Besides, finite element results show that elastic mismatch results in a significantly change in the distribution of stress intensity factor amplitude.
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Zhu, Juner, Yong Xia, Gongyao Gu, and Qing Zhou. "Extension of Non-Associated Hill48 Model for Characterizing Dynamic Mechanical Behavior of a Typical High-Strength Steel Sheet." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36985.
Повний текст джерелаАнотація:
Sheet metals usually exhibit a certain degree of plastic anisotropy because of the rolling effect. To characterize the anisotropic behavior in simulations related to large deformation, strain-rate independent phenomenological models are frequently used in quasi-static conditions. Two functions are generally included in such a model, i.e. the yield function and the plastic potential. The former limits the stress state within the yield surface while the latter determines the direction of the plastic strain increment. Traditional plasticity models mostly assume associated flow rule, in which the two functions mentioned above are identical. With the enhanced demand of accuracy, the forms of the associated models become too complex with more and more parameters to achieve an easy calibration procedure. Alternatively, in the past decade the non-associated models were increasingly used for sheet metals. Separate functions for the two aspects of plasticity lead to efficient characterization and convenient calibration. In numerical study of dynamic loading cases, how to characterize strain-rate dependence of plasticity is an important issue. Some visco-plastic models were developed to take the rate effect into account, e.g. Johnson-Cook and Cowper-Symonds models, where the isotropic J2 flow theory was commonly used. However, when the material is severely anisotropic, this approach is very likely to be insufficient, and a model including both anisotropy and rate dependence would be needed. Extending a non-associated anisotropic model to be rate-dependent is a promising approach which has not been published in open literature to the best knowledge of the authors. Objective of the present study is to develop an applicable model for characterizing dynamic mechanical behavior of a typical high-strength steel sheet. Two steps are performed. The material is investigated under quasi-static loading firstly. Tensile test results show an obvious anisotropy which cannot be described by traditional associated models. So the non-associated Hill48 model is chosen and calibrated. Accuracy of the model is verified by a quasi-static punching test. Thereafter the dynamic material properties are obtained by conducting tensile tests at quite a few strain-rate levels covering 0.0004–1200s−1. To characterize the positive strain-rate effect in strength, the non-associated Hill48 model is extended to be visco-plastic after checking two rate-dependence formulations in existing isotropic models. With implementing the extended model into a user subroutine of ABAQUS/explicit, simulations of the dynamic tension tests are run and compared to the real experiments. A good agreement between the simulated and the experimental result is achieved using the VUMAT.
Звіти організацій з теми "Rate-dependent strength behaviour"
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TENSILE BEHAVIOUR OF TMCP Q690D HIGH-STRENGTH STRUCTURAL STEEL AT STRAIN RATES FROM 0.00025 TO 760 S-1. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.7.
Повний текст джерелаАнотація:
The application of Q690D high-strength structural steel (HSSS) has been increasing in engineering structures. The lack of knowledge of the strain rate behaviour limits the application to the extreme loading conditions such as blast and impact loadings. This paper presents a series of tensile tests on the dynamic tensile behaviour of Q690D HSSS produced through the thermo-mechanical control process (TMCP). The stress-strain relationships of TMCP Q690D in the strain rate range of 0.00025 to 760 s-1 were measured by using the universal and servo-hydraulic high speed testing machines. The experimental results verified the sensitivity to strain rate of TMCP Q690D and the dynamic increase factor (DIF) for yield stress is identical to that of QT (Quenched and Tempered) S690 HSSS. However, TMCP Q690D behaves in a much different way in the strain hardening stage. The commonly-used Cowper-Symonds model was calibrated for the DIFs of yield stress and ultimate tensile strength. The Johnson-Cook (J-C) model was modified and a new rate-dependent constitutive model was proposed. The proposed model was validated successfully to predict the true stress-strain relationship, providing better prediction results than the modified J-C model.