Journal articles: 'Quasi-static process'

1

Kitsunezaki, S., and A. Kurumatani. "The Creation Process of Faults in Quasi-static Deformation." Granular Matter 5, no. 4 (2004): 185–92. http://dx.doi.org/10.1007/s10035-003-0150-x.

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Pavelko, Vitalijs. "On the Crack Quasi-Static Growth." Key Engineering Materials 827 (December 2019): 312–17. http://dx.doi.org/10.4028/www.scientific.net/kem.827.312.

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The theoretical model of quasi-static crack growth in the elastic-plastic material under load variation in a wide range. Small-scale yielding is principal assumption and main restriction of proposed theory. The model of crack growth provides for continues and interrelated both the crack propagation and plastic deformation development. The nonlinear first-order differential equation describes the quasi-static process of crack growth. In dimensionless form this equation invariant in respect to geometrical configuration and material. The critical size of the plastic zone is proposed as the characteristics of material resistance which is directly connected with the fracture toughness, but more convenient in practical applications of invariant equation. The demonstration of solution is performed for the double cantilever beam that widely used as the standard (DCB) sample for measurement of the mode-I interlaminar fracture toughness. he short analysis of some properties of solution of the invariant equation and its application is done.

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Messelmi, Farid, Abdelbaki Merouani, and Hicham Abdelaziz. "Quasi-Static Linear Thermo-Viscoelastic Process with Irregular Viscous Dissipation." Advances in Applied Mathematics and Mechanics 9, no. 4 (2017): 924–43. http://dx.doi.org/10.4208/aamm.2014.m656.

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AbstractWe consider a mathematical model which describes the quasi-static evolution of a thermo-viscoelastic linear body with taking into account the effects of internal forces which generate a non linear viscous dissipative function. We derive a variational formulation of the system of equilibrium equation and energy equation. An existence result of weak solutions was obtained in an appropriate function space.

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Cui, Xiaohui, Zhiwu Zhang, Hailiang Yu, Xiaoting Xiao, and Yongqi Cheng. "Springback Calibration of a U-Shaped Electromagnetic Impulse Forming Process." Metals 9, no. 5 (2019): 603. http://dx.doi.org/10.3390/met9050603.

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A three-dimensional (3D) finite-element model (FEM), including quasi-static stamping, sequential coupling for electromagnetic forming (EMF) and springback, was established to analyze the springback calibration by electromagnetic force. Results show that the tangential stress at the sheet bending region is reduced, and even the direction of tangential stress at the bending region is changed after EMF. The springback can be significantly reduced with a higher discharge voltage. The simulation results are in good agreement with the experiment results, and the simulation method has a high accuracy in predicting the springback of quasi-static stamping and electromagnetic forming.

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Sun, De Qiang, Yan Feng Guo, and Guo Tu Xu. "In-Plane Crushing of Triangular Honeycomb Cores, Part I: Under Quasi-Static Loadings." Advanced Materials Research 476-478 (February 2012): 2501–4. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.2501.

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Mechanical behaviors of triangular honeycombs cores (THCs) are investigated by using the finite element (FE) simulations under the in-plane quasi-static crushing loadings. The deformation process is described in the form of response curves and deformation mode diagrams. The force-displacement curves include four deformation regimes with distinct characteristics. The quasi-static plateau stresses are calculated for the THCs with different configuration parameters. The influences of ratio of cell wall thickness to edge length and expanding angle on the quasi-static plateau stress are discussed in detail. The quasi-static plateau stress is proportional to the relative density of THCs and the expanding angle determines the scale coefficient. The empirical formula of quasi-static plateau stress in terms of ratio of cell wall thickness to edge length and expanding angle is given based on the FE simulation results.

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Thomas, Mathew S., Demetra Z. Adrahtas, C. Daniel Frisbie, and Kevin D. Dorfman. "Modeling of Quasi-Static Floating-Gate Transistor Biosensors." ACS Sensors 6, no. 5 (2021): 1910–17. http://dx.doi.org/10.1021/acssensors.1c00261.

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Ogorelkov, Dmitriy, Vladimir Mironov, and Olga Lukashuk. "Durability of metal structures under quasi-static load." MATEC Web of Conferences 224 (2018): 02091. http://dx.doi.org/10.1051/matecconf/201822402091.

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Failure of materials and structures is one of unresolved problems of mechanics. This paper offers an approximate approach to assessing durability of products on the basis of a mechanical experiment. The experiment represents the fatigue process as a transition of a plastic material into its brittle state. A simplified physical model – which could be used to build a mathematical model of fatigue process – hangs on a local transition of a plastic material into its brittle state. The calculation methodology includes both an original part on cyclic degradation of material strength and correlations based on experiments and checked by design routines. Two approaches to calculating the durability of a randomly-loaded object are compared: using the equation of cyclic degradation of strength and the rule of linear summation of fatigue damages. The results obtained are useful for improving methodologies of calculating service life or durability of structures.

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Yan, Kun, Shiyou Wu, and Guangyou Fang. "Detection of Quasi-Static Trapped Human Being Using Mono-Static UWB Life-Detection Radar." Applied Sciences 11, no. 7 (2021): 3129. http://dx.doi.org/10.3390/app11073129.

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In practical situations such as hostage rescue, earthquake and other similar events, the ultra-wideband (UWB) life-detection radar echo response from the respiration motion of the trapped person is always quasi-/non-periodic in respiration frequency or very weak in respiration amplitude, which can be called quasi-static vital sign. Although it is an extremely difficult task, considering the economic cost, the detection ability of the traditional UWB life-detection radars with only a pair of transceiver antennas is desired to be enhanced for locating the quasi-static trapped human being. This article proposes two different detection methods for quasi-static trapped human beings through the single/multiple observation points, which corresponds to the single-/multi-station radar operating mode, respectively. Proof-of-principle experiments were carried out by our designed radar prototypes, validating the effectiveness of the proposed methods.

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Zhu, Hongwei, Yaodong Feng, Danfeng Lu, et al. "Dynamics of quasi-static collapse process of a binary granular column." Powder Technology 339 (November 2018): 970–73. http://dx.doi.org/10.1016/j.powtec.2018.08.051.

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Pan, Bei-Cheng, Qing-Fan Shi, and Gang Sun. "Experimental Observation of Quasi-Static Avalanche Process of a Granular Pile." Chinese Physics Letters 30, no. 12 (2013): 124701. http://dx.doi.org/10.1088/0256-307x/30/12/124701.

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MANABE, Kazuyoshi, and Ken NAKANO. "The Breakdown Process of Hexadecane Films Induced by Quasi-Static Loading." Journal of Advanced Mechanical Design, Systems, and Manufacturing 1, no. 5 (2007): 640–48. http://dx.doi.org/10.1299/jamdsm.1.640.

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Gao, Fuqiang, Hongpu Kang, and Lei Yang. "An Experimental Investigation into the Strainburst Process Under Quasi-static Loading." Rock Mechanics and Rock Engineering 53, no. 12 (2020): 5617–29. http://dx.doi.org/10.1007/s00603-020-02231-y.

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13

Rozgić, Marco, Yalin Kiliclar, Marcus Stiemer, and Stefanie Reese. "Virtual process design on combined quasi-static and high-speed forming." PAMM 15, no. 1 (2015): 577–78. http://dx.doi.org/10.1002/pamm.201510278.

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Li, Meng, Ying Liu, Jinwen Ye, Jun Li, and Mingjing Tu. "Process and quasi-static compressive properties of highly porous palladium bulks." Journal of Porous Materials 15, no. 6 (2007): 715–18. http://dx.doi.org/10.1007/s10934-007-9158-7.

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15

Li, Yi, Youwei Zhang, Haiwei Dong, Wenjie Cheng, Chaoming Shi, and Jiangying Chen. "Dynamic Response of Electro-Mechanical Properties of Cement-Based Piezoelectric Composites." Applied Sciences 11, no. 24 (2021): 11925. http://dx.doi.org/10.3390/app112411925.

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By employing ordinary Portland cement as a matrix and PZT-5H piezoelectric ceramic as the functional body, 1-3 and 2-2 cement-based piezoelectric composites were prepared. Quasi-static compression tests were performed along with dynamic impact loading tests to study the electro-mechanical response characteristics of 1-3 and 2-2 cement-based piezoelectric composites. The research results show that both composites exhibit strain rate effects under quasi-static compression and dynamic impact loading since they are strain-rate sensitive materials. The sensitivity of the two composites has a non-linear mutation point: in the quasi-static state, the sensitivity of 1-3 and 2-2 composites is 157 and 169 pC/N, respectively; in the dynamic state, the respective sensitivity is 323 and 296 pC/N. Although the sensitivity difference is not significant, the linear range of the 2-2 composite is 24.8% and 61.3% larger than that of the 1-3 composite under quasi-static compression and dynamic impact loading, respectively. Accordingly, the 2-2 composite exhibits certain advantages as a sensor material, irrespective of whether it is subjected to quasi-static or dynamic loading.

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Muiruri, Amos, Maina Maringa, and Willie du Preez. "Quasi-Static Mechanical Properties of Post-Processed Laser Powder Bed Fusion Ti6Al4V(ELI) Parts under Compressive Loading." Applied Sciences 12, no. 19 (2022): 9552. http://dx.doi.org/10.3390/app12199552.

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The Ti6Al4V structures in aircraft and biomedical industries are usually exposed to quasi-static loads. Therefore, understanding the quasi-static behaviour of this alloy manufactured by an additive manufacturing process is paramount. This paper documents an investigation of the quasi-static mechanical properties of various microstructures of heat-treated Ti6Al4V(ELI) parts manufactured by laser powder bed fusion (LPBF). The effects of different quasi-static strain rates on different microstructures of these samples and their strain hardening are also presented. The test samples were produced using an EOSINT M280 direct metal laser sintering (DMLS) machine and, thereafter, subdivided into three major groups, namely samples C, D and E, for high-temperature annealing at different heat treatment strategies. A universal hydraulic testing machine (UTM) was used to carry out tests at strain rates of 0.001 s−1, 0.005 s−1 and 0.1 s−1. The three forms of LPBF Ti6Al4V(ELI) were found to be sensitive to quasi-static strain rate, whereby values of yield and flow stresses in each form of alloy increased with increasing strain rate. The order of the strength at each strain rate from the highest to the lowest was found to be samples C, D and E. The effects of strain rate on flow hardening were found to be significant in samples C and insignificant in samples D and E.

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KABLA, ALEXANDRE, and GEORGES DEBREGEAS. "Quasi-static rheology of foams. Part 1. Oscillating strain." Journal of Fluid Mechanics 587 (August 31, 2007): 23–44. http://dx.doi.org/10.1017/s0022112007007264.

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A quasi-static simulation is used to study the mechanical response of a disordered bidimensional aqueous foam submitted to an oscillating shear strain. The application of shear progressively extends the elastic domain, i.e. the strain range within which no plastic process occurs. It is associated with the development of an irreversible normal stress difference, and a decrease in the shear modulus, which are both signatures of the appearance of anisotropy in the film network. Beyond this mechanical measurement, the evolutionof the structural properties of the foam is investigated. We focus in particular on the energy E0 defined as the minimum line-length energy under zero shear stress. For strainamplitude less than ~0.5, this quantity is found to decay with the number of applied cycles as a result of the curing of topological defects. However, for higher strain amplitude, plastic events appear to increase the structural disorder and tend to gather near the shearing walls. This process is a precursor of the shear-banding transition observed in fully developed flows, which will be studied in the companion paper. Movies are available with the online version of the paper.

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Hsu, Ivan Yao. "Quasi-Static Failure Analysis of Composite Sandwich Panels." Applied Mechanics and Materials 121-126 (October 2011): 316–19. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.316.

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Due to many of advantages such as lightweighted, high-bending mechanical characteristics, composite sandwich materials play an important role in today’s structural manufacturing industry. This study is to aim at the low-velocity impact responses of sandwich plates subjected to a rigid, spherical-shaped impactor. The sandwich made of PVC core material (two kinds of core with different densities) and FRP facesheets (three kinds of fibrous laminae) were investigated experimentally and numerically. Because the dynamic behaviors of specimens due to low velocity impact is nearly the same to those in static indentation, the impact failure analysis of sandwich material can be simulated statically. Beside the experiment, finite element method was employed to analyze the static failure behaviors of sandwich panels. With the maximum stress failure criterion as well as a modified stiffness degradation method coded in the finite element software, the initial failure and sequential progressive failure process can be analyzed effectively.

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Sera, Toshihiro, Kentaro Uesugi, and Naoto Yagi. "Morphometric Deformations of Small Airways and Alveoli under Quasi-static Inflation Process." Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science 24, no. 4 (2005): 465–68. http://dx.doi.org/10.2114/jpa.24.465.

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Rozgić, Marco, Farhad Taebi, and Marcus Stiemer. "Numerical optimisation of process parameters for combined quasi-static and impulse forming." PAMM 12, no. 1 (2012): 625–26. http://dx.doi.org/10.1002/pamm.201210301.

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21

Perin, Davide, Giada Odorizzi, Andrea Dorigato, and Alessandro Pegoretti. "Development of Polyamide 6 (PA6)/Polycaprolactone (PCL) Thermoplastic Self-Healing Polymer Blends for Multifunctional Structural Composites." Applied Sciences 12, no. 23 (2022): 12357. http://dx.doi.org/10.3390/app122312357.

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High-performance composites suffer from fatigue crack propagation during service. Traditional repair methods can be expensive and time-consuming. Therefore, research on composites with self-healing capabilities has considerably increased in the past decade. The aim of this work is to develop a polyamide 6 (PA6) matrix with self-healing properties. Polycaprolactone (PCL) was used as healing agent and melt compounded with PA6. PCL caused a decrease of the mechanical properties of PA6, due to its immiscibility and low mechanical properties. Nevertheless, acceptable fracture toughness values in quasi-static mode were obtained. Samples were thermally mended at 80 and 100 °C, and the healing efficiency was assessed by comparing the fracture toughness of virgin and repaired samples both in quasi-static and in impact mode. The blend with a PCL content of 30 wt% showed limited healing efficiency values (up to 6%) in quasi-static mode, while an interesting repair capability (53%) was detected under impact conditions. This discrepancy was explained through microstructural analysis and correlated to a different fracture morphology. In fact, under quasi-static mode, the PA6 matrix was severely plasticized, while under impact a brittle fracture surface was obtained. This morphology favored the flow of PCL during the thermal healing process.

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Kawasaki, Tsutomu. "General Theory off Quasi-Static Linear Gradient Chromatography." Separation Science and Technology 22, no. 1 (1987): 121–39. http://dx.doi.org/10.1080/01496398708056162.

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Liu, W., H. Zhou, Z. Meng, J. Li, and S. Huang. "Less damage accumulation of aluminum alloy sheet during electromagnetic forming based on Gurson-Tvergaard-Needleman model." IOP Conference Series: Materials Science and Engineering 1238, no. 1 (2022): 012019. http://dx.doi.org/10.1088/1757-899x/1238/1/012019.

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Abstract The formability of aluminum alloy sheet is usually improved during electromagnetic forming (EMF). Here, the ductility enhancement mechanism was investigated on the basis of Gurson-Tvergaard-Needleman (GTN) model. The parameters of GTN models under quasi-static tension and EMF conditions were respectively determined by inverse identification. For AA2024-O aluminum alloy sheet under quasi-static tension, the initial void volume fraction is identified as 0.006, the critical void volume fraction where voids begin to aggregate is 0.075, the void volume fraction of nucleating particles is 0.131 and the mean nucleation strain is 0.44. With the similar initial void volume fraction, the other parameters under EMF condition are determined as 0.045, 0.055 and 0.58. The evolution curve of void volume fraction with strain were compared under EMF condition and quasi-static tension. The results show that the total growth of void volume fraction is less under EMF condition than that under quasi-static tension. A box part with inclined flange was preliminary achieved by electromagnetic forming process. The GTN model was finally verified by comparing the numerical and experimental results.

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Csomós, Zilia, and János Lukács. "Fatigue Crack Growth Tests on Glass Fibre Reinforced Polymer Matrix Composite." Materials Science Forum 473-474 (January 2005): 189–94. http://dx.doi.org/10.4028/www.scientific.net/msf.473-474.189.

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E-glass fibre reinforced polyester matrix composite was investigated, which was made by pullwinding process. Round three point bending (RTPB) specimens were tested under quasi-static and mode I cyclic loading conditions. Load vs. displacement (F-f), load vs. crack opening displacement (F-v) and crack opening displacement range vs. number of cycles (ΔCOD-N) curves were registered and analysed. Interfacial cracks were caused the final longitudinal fracture of the specimens under quasi-static and cyclic loading conditions.

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Bulian, Gabriele. "Time-based damaged ship survivability: A quasi-static equivalent method." International Shipbuilding Progress 55, no. 3 (2008): 183–226. https://doi.org/10.3233/isp-2008-0047.

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This paper presents a series of ideas to make a step forward in the assessment of flooded ship survivability on a time-dependent basis. An extension of the SEM (Static Equivalent Method) to a Quasi-Static Equivalent method (QSEM) is proposed to take into account the time variable and to address the case of multiple compartments. A capsize index based, conceptually, on static calculations is defined as a function of time and sea state. Capsize is considered in terms of both a first-excursion problem concerning the wave amplitude, and as the persistence of high-runs of waves above a critical level. An example of the proposed methodology is presented for the analysis of the flooding a two decks. Using the same hydraulic model, comparisons are carried out between the presented approximate analytical methodology and direct numerical simulations of the flooding process to assess the effect of downflooding means. A discussion is given on how the time-based approach to ship survivability links with the evacuation process, in order to obtain the probability density function of the number of evacuated passengers.

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Azwan, Syed Mohd Saiful, Yahya Mohd Yazid, Ayob Amran, and Behzad Abdi. "Quasi-Static Indentation Behaviour of Glass Fibre Reinforced Polymer." Advanced Materials Research 970 (June 2014): 317–19. http://dx.doi.org/10.4028/www.scientific.net/amr.970.317.

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Fibre reinforced polymer (FRP) plates subject to quasi-static indentation loading were studied. The plates were fabricated from three layers of chopped strand mat glass fibre and polyester resin using vacuum infusion process. Indentation tests were conducted on the plates with loading rates of 1 mm/min, 10 mm/min, 100 mm/min and 500 mm/min using a hemispherical tip indenter with diameter 12.5 mm. The plates were clamped in a square fixture with an unsupported space of 100 mm × 100 mm. The loads and deflections at the indented location were measured to give energy absorption-deflection curves. The results showed that the loading rate has a large effect on the indentation behaviour and energy absorbed.

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27

Gunaydin, Kadir, Aykut Tamer, Halit Suleyman Turkmen, Giuseppe Sala, and Antonio Mattia Grande. "Chiral-Lattice-Filled Composite Tubes under Uniaxial and Lateral Quasi-Static Load: Experimental Studies." Applied Sciences 11, no. 9 (2021): 3735. http://dx.doi.org/10.3390/app11093735.

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Our research investigated the energy absorption characteristics of chiral auxetic lattices filled cylindrical composite tubes subjected to a uniaxial and lateral quasi-static load. The lattice structures were manufactured using a 3D printing technique. Carbon fiber composite tubes without filler material were initially subjected to uniaxial and lateral quasi-static crushing load. The same types of experiment were then performed on chiral lattices and chiral lattices filled composite tubes. For the different cases, the load–displacements curves were analyzed and the specific energy absorption (SEA) values were compared. The SEA capability for the axial quasi-static crushing of the chiral lattices filled composite tubes decreased in comparison with the hollow composite design. However, the most significant result was that the average SEA value in the case of lateral loading increased dramatically in comparison with the hollow composite configuration.

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Gozdur, Roman. "Study of Quasi-Static Magnetization with the Random-Field Ising Model." Algorithms 13, no. 6 (2020): 134. http://dx.doi.org/10.3390/a13060134.

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The topic of this paper is modeling based on Hamiltonian spin interactions. Preliminary studies on the identification of quasi-static magnetizing field in a magnetic system were presented. The random-field Ising model was then used to simulate the simplified ferromagnetic structure. The validation of algorithms and simulation tests were carried out for the 2D and the 3D model spaces containing at least 106 unit cells. The research showed that the response of a slowly driven magnetic system did not depend on the external field sweep rate. Changes in the spatial magnetization of the lattice were very similar below a certain rate of the external field change known as the quasi-static boundary. The observed differences in obtained magnetization curves under quasi-static conditions stemmed from the random nature of the molecular field and the avalanche-like magnetization process

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Hamdan, S., W. Dwianto, T. Morooka, and M. Norimoto. "Softening Characteristics of Wet Wood under Quasi Static Loading." Holzforschung 54, no. 5 (2000): 557–60. http://dx.doi.org/10.1515/hf.2000.094.

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Summary In order to examine the possible influences of temperature on the wood constituents, two groups of wood species namely softwood (needle leaf wood) and hardwood (broad leaf wood) were subjected to heat or steam treatment during large radial compression between 0°C and 200°C. Two well-defined softening regions are observed. Both species showed the glass transition Tg of lignin at ~ 90°C and ~ 60°C for softwood and hardwood respectively and a second transition region at ~ 160°C. The softening behavior between the first and second transition in softwood is in contrast with the softening behavior of hardwood. This difference reflects the difference in the distribution of the relaxation process due to lignin, which suggests the difference in chemical structure of lignin between softwood and hardwood.

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Zhang, Hong Shuang. "Numerical Simulation of Riveting Process." Applied Mechanics and Materials 34-35 (October 2010): 641–45. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.641.

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In order to fully understanding the distribution of residual stress after riveting and the relationship between residual stress and riveting process parameters during riveting, Finite Element Method was used to establish a riveting model. Quasi-static method to solve the convergence difficulties was adopted in riveting process. The riveting process was divided into six stages according to the stress versus time curves. The relationship of residual stress with rivet length and rivet hole clearance were established. The results show numerical simulation is effective for riveting process and can make a construction for the practical riveting.

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Yu, Xiaozhe, Xingqing Yan, Yue Li, Fangchi Zeng, Shouli Kang, and Jianliang Yu. "Determination of the Plastic Stress–Strain Relationship of a Rupture Disc Material with Quasi-Static and Dynamic Pneumatic Bulge Processes." Processes 10, no. 8 (2022): 1463. http://dx.doi.org/10.3390/pr10081463.

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Rupture discs, manufactured using a hydraulic or pneumatic bulge process, are widely used to protect vessels from over-pressuring. The stress–strain relationship of the material in the bulge process plays a major role in understanding the performance of rupture discs. Moreover, both the theoretical analyses and numerical simulations of rupture discs demand a reliable stress–strain relationship of the material in a real bulge process. In this paper, an approach for determining the plastic stress–strain relationship of a rupture disc material in the bulge process is proposed based on plastic membrane theory and force equilibrium equations. Pressures of compressed air and methane/air mixture explosions were used for the bulge pressure to accomplish the quasi-static and dynamic bulge processes of tested discs. Experimental apparatus for the quasi-static bulge test and the dynamic bulge test were built. The stress–strain relations of 316L material during bulge tests were obtained, compared, and discussed. The results indicated that the bulge height at the top of the domed disc increased linearly with an increase in bulge pressure in the quasi-static and dynamic bulge processes, and the effective strain increased exponentially. The rate of pressure rise during the bulge process has a significant effect on the deformation behavior of disc material and hence the stress–strain relationship. At the same bulge pressure, a disc tested with a larger pressure rise rate had smaller bulge height and effective strain. At the same effective stress at the top of the domed disc, discs subjected to a higher pressure rise rate had smaller effective strain, and hence they are more difficult to rupture. Hollomon’s equation is used to represent the relationship between the effective stress and strain during bulge process. For pressure rise rates in the following range of 0 (equivalent to quasi-static condition), 2–10 MPa/s, 10–50 MPa/s, and 50–100 MPa/s, the relation of stress and strain is σe = 1259.4·εe0.4487, σe = 1192.4·εe0.3261, σe = 1381.2·εe0.2910, and σe = 1368.4·εe0.1701, respectively.

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Jin Xin-Xin, Jin Feng, Liu Ning, and Sun Qi-Cheng. "Analysis of elastic energy relaxation process for granular materials at quasi-static state." Acta Physica Sinica 65, no. 9 (2016): 096102. http://dx.doi.org/10.7498/aps.65.096102.

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Zhang, Hangyue, Rong Cai, Yanchu Yang, and Rong Zhao. "Quasi-static numerical simulation of the dynamic launching process for high-altitude balloon." Aerospace Science and Technology 117 (October 2021): 106830. http://dx.doi.org/10.1016/j.ast.2021.106830.

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Luo, Yinfeng, Cheng Zhao, Yuan Qian, Jinquan Xing, and Biaohe Zhou. "Damage Evolution and Energy Catastrophe Behavior during Quasi-static Loading Process of Rockburst." IOP Conference Series: Earth and Environmental Science 1334, no. 1 (2024): 012033. http://dx.doi.org/10.1088/1755-1315/1334/1/012033.

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Abstract Rockburst pose a serious hazard to deep underground engineering. The damage evolution and energy transformation of rockburst under quasi-static load are the key to reveal the mechanism of rockburst. Based on the instability theory and stiffness theory, the burst rock and surrounding rock combination specimens are designed in this study. Then a constitutive model for simulating the whole process of rockburst is established by statistical damage of rock. The law of damage deformation and energy evolution during rockburst is revealed, and the key factors affecting rockburst intensity are analyzed. The results indicate that the damage mechanism of rockburst is related to the sudden change of damage before and after the peak stress of the burst rock, and the volume ratio of surrounding rock to burst rock. The evaluation index of rockburst proneness based on energy evolution can reflect the energy conversion and transmission relationship between the surrounding rock and burst rock in the combination system, which is of great significance for the evaluation of rockburst proneness.

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Fujisawa, N., and M. V. Swain. "Mechanical properties characterization of a viscoelastic solid using low-frequency large-amplitude oscillatory indentations with a sharp tip." Journal of Materials Research 23, no. 6 (2008): 1557–63. http://dx.doi.org/10.1557/jmr.2008.0211.

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A viscoelastic solid was contacted by a pointed indenter using low-frequency large-amplitude sinusoidal load functions to determine its contact stiffness in a manner similar to that of the continuous stiffness measurement (CSM) technique but in a quasi-static condition. The contact stiffness of a viscoelastic solid determined by the CSM technique, or the dynamic stiffness, is known, from previous CSM-based studies, to overestimate the quasi-static contact stiffness. The contact stiffness of a viscoelastic solid determined in a quasi-static manner is thus hypothesized to help predict the contact depth more accurately. A new analysis procedure based on truncated Fourier series fitting was developed specifically to process the large amplitude sinusoidal indentation data. The elastic modulus of the material characterized in this work was in agreement with that determined by dynamic mechanical analysis, thereby providing evidence for the validity of the present method in characterizing other viscoelastic materials.

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FIEDKIEWICZ, Łukasz, and Ireneusz PIELECHA. "Selection of ion sensor operating parameters in quasi-static conditions." Combustion Engines 179, no. 4 (2019): 254–58. http://dx.doi.org/10.19206/ce-2019-442.

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Evaluating combustion quality using sensors that allow continuous assessment of the process is one of the modern methods of engine sensory diagnostics. The proper calibration of such systems is a task that requires many studies to determine the conditions and quantities affecting the process. The analysis of significance of quantities related to the ionization signal was carried out in the article. The magnitude of the voltage generating the electric field, the type of spark plug used, the distance of the spark plug electrodes and the dynamic factor – spark plug operating temperature – were all tested. The tests were carried out using a CNG burner (with an excess air ratio of lambda = 1) and four spark plugs. As a result of the ionization signal research, the following relationships were obtained: regarding the impact of the sensor position on the amount of generated voltage (the smaller the distance the greater the value of the signal), the effect of temperature on the sensor resistance (non-linear relationship: increase in temperature decreases resistance, with R2 = 0.9997) effect of system voltage on the ionization signal (linear relationship: voltage increase increases the ionization current signal with a determination coefficient of R2 = 0.9803). In addition, it was found that using an iridium electrode candle had the best effects on the ionization current, regardless of the electrode’s geometrical parameters.

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Kiliclar, Yalin, O. Koray Demir, Ivaylo N. Vladimirov, Lukas Kwiatkowski, Stefanie Reese, and A. Erman Tekkaya. "Simulation of Electromagnetic Forming of a Cross-Shaped Cup by Means of a Viscoplasticity Model Coupled with Damage at Finite Strains." Key Engineering Materials 554-557 (June 2013): 2363–68. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.2363.

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In the field of sheet metal forming traditional forming processes are used. However, a quasi-static forming process combined with a high speed forming process can enhance the forming limits of a single one. In this paper, the investigation of the process chain quasi-static deep drawing – electromagnetic forming by means of a new coupled damage-viscoplasticity model for large deformations is performed. The finite strain constitutive model, used in the finite element simulation combines nonlinear kinematic and isotropic hardening and is derived in a thermodynamically consistent setting. The anisotropic viscoplastic model is based on the multiplicative decomposition of the deformation gradient in the context of hyperelasticity. The kinematic hardening component represents a continuum extension of the classical rheological model of Armstrong–Frederick kinematic hardening. Hill-type plastic anisotropy is modelled by expressing the yield surface as a function of second-order structure tensors as additional tensor-valued arguments. The coupling of damage and plasticity is carried out in a constitutive manner according to the effective stress concept. The constitutive equations of the material model are integrated in an explicit manner and implemented as a user material subroutine in the commercial finite element package of LS-Dyna with the electromagnetical modul. Aim of the work is to show the increasing formability of the sheet by combining quasi-static deep drawing processes with high speed electromagnetic forming process.

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Mauko, Anja, Tomáš Fíla, Jan Falta, et al. "Dynamic Deformation Behaviour of Chiral Auxetic Lattices at Low and High Strain-Rates." Metals 11, no. 1 (2020): 52. http://dx.doi.org/10.3390/met11010052.

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The mechanical behaviour of three different auxetic cellular structures, hexa-chiral 2D, tetra-chiral 2D and tetra-chiral 3D, was experimentally investigated in this study. The structures were produced with the powder bed fusion method (PBF) from an austenitic stainless steel alloy. The fundamental material mechanical properties of the sample structures were determined with classic quasi-static compressive tests, where the deformation process was captured by a high-resolution digital camera. The Split Hopkinson Pressure Bar (SHPB) apparatus was used for dynamic impact testing at two impact velocities to study the strain-rate dependency of the structures. Two synchronised high-speed cameras were used to observe the impact tests. The captured images from both quasi-static and dynamic experiments were processed using a custom digital image correlation (DIC) algorithm to evaluate the displacement/strain fields and the Poisson’s ratio. Predominant auxetic behaviour was observed in all three structures throughout most of the deformation process both under quasi-static and impact loading regimes. The tetra-chiral 2D structure showed the most significant auxetic behaviour. Significant stress enhancement in all tested structures was observed in dynamic testing. The Poisson’s ratio strain-rate dependency was confirmed for all three auxetic structures.

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Tan, Na, Liyang Lin, Tao Deng, and Yongwu Dong. "Evaluating the Residual Stress and Its Effect on the Quasi-Static Stress in Polyethylene Pipes." Polymers 14, no. 7 (2022): 1458. http://dx.doi.org/10.3390/polym14071458.

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Residual stress is generated during the production process. It can significantly affect the mechanical performance of pressurized polymer pipes. In this paper, six polyethylene (PE) pipes, including three high-density PEs (HDPE) and three medium-density PEs (MDPE) provided by different suppliers, were tested using a one-slit-ring method to measure the residual stress distribution along the hoop direction. Finite element (FE) simulation and mechanical testing were also employed in an iteration process to obtain the mechanical parameters of the six PE pipes. For the same PE pipe code from different suppliers, the results show that the magnitude of the residual hoop stress can be very different, resulting in different mechanical behaviors. In addition, the results are proposed to explain the scenario that was reported previously, i.e., the different critical quasi-static stress (the time-independent stress) levels of the PE pipes with the same pipe code. Since the quasi-static stress is expected to dominate the long-term behavior of the PE pipes, it is of great importance to carefully consider the effect of the residual stress on the determination of the quasi-static stress.

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Wang, L. Q., Y. K. Wen, F. D. Dong, B. Qin, Y. Qu, and F. Sun. "Quasi-static and dynamic mechanical characterization of clay and ballistic soap." Journal of Physics: Conference Series 2478, no. 12 (2023): 122041. http://dx.doi.org/10.1088/1742-6596/2478/12/122041.

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Abstract Ballistic gelatin, soap, and clay are three human simulated target materials commonly used in the field of wound ballistics research. Currently, there are more studies on ballistic gelatin’s mechanical properties, but rarely on clay and soap. In this paper, the mechanical properties of clay and soap materials were tested by using universal material testing machine and Hopkinson bar, respectively, and their stress-strain curves were obtained under different temperatures (4°C, 15°C, and 25°C) from quasi-static to dynamic loading. The test results showed that the clay material was sensitive to temperature and strain rate in quasi-static conditions, its stress-strain curves showed nonlinear strengthening characteristics, and the stress always increased without strength decrease during the loading process; the dynamic compression mechanical properties of clay were significantly higher than the quasi-static mechanical properties, showing obvious strain rate strengthening effect. In quasi-static compression experiments, the stress-strain curves of soap material showed bilinear elastic-plastic material characteristics; when the strain was less than 0.1, it was insensitive to temperature and strain rate, and only when the strain was more significant than 0.1 did it show a certain temperature and strain rate correlation. The dynamic compressive mechanical properties of soap are significantly higher than the quasi-static mechanical properties, showing a significant strain-rate strengthening effect. The stress of soap at the same strain rate is slightly less than that of clay. These results not only help provide more accurate material parameters for relevant numerical calculations but also help to provide references for the development of new bionic materials.

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Zhu, Jianjian, Xinlin Qing, Qijian Liu, Xiao Liu, and Yishou Wang. "Monitoring of Fiber-Reinforced Composite Single-Lap Joint with Electromechanical Impedance of Piezoelectric Transducer." Materials 12, no. 19 (2019): 3241. http://dx.doi.org/10.3390/ma12193241.

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The single-lap joint of fiber-reinforced composites is a common structure in the field of structure repair, which has excellent mechanical properties. To study and monitor its quasi-static response behavior under external load, two methodologies called effective structural mechanical impedance (ESMI) and reduced-ESMI (R-ESMI) are presented in this article. A two-dimensional electromechanical impedance (EMI) model for a surface-bonded square piezoelectric transducer (PZT) is adopted to extract more sensitive signatures from the measured raw signatures. There are two major advantages of the monitoring scheme based on ESMI and R-ESMI signatures: (1) excellent monitoring results with less signatures to process, (2) the ability to monitor the quasi-static behavior of a single-lap joint with previously ignored susceptance signatures. Combining the extracted ESMI signatures with the index of root-mean-square deviation, the quasi-static behavior of single-lap joints can be effectively quantified. To test the effectiveness of ESMI methodology, verifying experiments were conducted. The experimental results convincingly demonstrated that the presented ESMI and R-ESMI methodologies have good feasibility in monitoring the quasi-static behavior of a fiber-reinforced composite single-lap joint. The proposed method has potential application in the field of structural health monitoring (SHM).

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Wu, Zhe, Hai Feng Jiang, Yang Zhang, Shuai Zhao, Chun Mei Yang, and Qing Nan Wang. "Effect of Different Particle Size Hollow Microbeads on the Mechanical Diffraction Process of Epoxy Resin Composites." Materiale Plastice 59, no. 4 (2001): 12–27. http://dx.doi.org/10.37358/mp.22.4.5622.

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The industrial grade hollow beads were divided into three particle sizes of 40 mesh, 60 mesh and 80 mesh and added into the epoxy resin material matrix to prepare porous foam composites. The quasi-static compression experiments were performed on porous foam composites at room temperature, and the stress-strain curves of quasi-static compression processes were analyzed separately for different particle sizes. According to the characteristics of the compression curve of porous foam materials, the representative characteristic parameters of each stage are extracted separately. The fracture characteristics of the microscopic samples of the compressed material specimens were observed by electron microscopy, and the deformation patterns of the composite materials were analyzed. And combined with SEM pictures to analyze the form of microbead crushing and matrix pore collapse mode, according to which the particle size suitable for this matrix is 60 mesh and the mass fraction of microbeads is 10%.

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Peterson, Viktor, Anders Ansell, and Mikael Hallgren. "On the Residual Static and Impact Capacity of Shear-Reinforced Concrete Beams Subjected to an Initial Impact." Applied Sciences 12, no. 22 (2022): 11377. http://dx.doi.org/10.3390/app122211377.

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Impact loads in previous research showed to induce brittle responses of statically flexure-critical reinforced concrete (RC) beams designed for ductility. The impact load may produce flexural shear damage modes similar to that observed during quasi-static loads and local shear damage under the impact zone. The occurrence of shear damage modes during impact tests has been investigated extensively, but their effect on the residual quasi-static and dynamic capacity is not fully understood. For this aim, an initial high-velocity impact test initiated severe shear damage to RC beams. The beams were then tested quasi-statically and by sequential impact testing using the same setup as the initial tests. The results indicate a flexure-dominated response during sequential impact tests for beams containing extreme shear reinforcement amounts, favouring the energy-absorption capacity. Significant shear and flexural damage occurred for beams with less shear reinforcement, indicating a hybrid response that varied throughout the tests. The tests for the residual quasi-static capacity indicated severe consequences from initial local shear damage on the capacity, as shown by the brittle response of the beam with the most shear reinforcement. However, wide initial flexural cracks instead showed a favourable effect, as there was an indication of transfer from brittle to ductile failure. For beams showing both global and local shear damage, it was concluded that global shear damage modes were critical for the residual static and dynamic shear capacity.

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Subhedar, Kiran M., Indu Sharma, and Sanjay R. Dhakate. "Control of layer stacking in CVD graphene under quasi-static condition." Physical Chemistry Chemical Physics 17, no. 34 (2015): 22304–10. http://dx.doi.org/10.1039/c5cp03541d.

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The contrast nature of layer stacking for the samples grown with different geometries of the reaction site suggests its different underlying growth mechanisms, originating from the process which supplies the extra carbon flux, needed for the growth of second layer.

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Yu, Jiayong, Zhen Fang, Xiaolin Meng, Yilin Xie, and Qian Fan. "Measurement of Quasi-Static and Dynamic Displacements of Footbridges Using the Composite Instrument of a Smartstation and an Accelerometer: Case Studies." Remote Sensing 12, no. 16 (2020): 2635. http://dx.doi.org/10.3390/rs12162635.

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Monitoring the dynamic responses of bridge structures has received considerable attention. It is important to synchronously measure both the quasi-static and dynamic displacements of bridge structures. However, the traditional accelerometer method cannot capture the quasi-static displacement component, although it can detect the dynamic displacement component. To this end, a novel composite instrument of a smartstation was proposed to monitor vibration displacements of footbridges. Full-scale experiments were conducted on a footbridge to validate the feasibility of the composite instrument-based monitoring method. A Chebyshev filter and wavelet algorithms were developed to process the composite instrument measurements. It was concluded that the measurement noise of the composite instrument was mainly distributed in a frequency range of 0–0.1 Hz. In two case studies with displacement peaks of 5.7–10.0 mm and 1.3– 2.5 mm, the composite instrument accurately identified the quasi-static and dynamic displacements. The composite instrument will be a potential tool for monitoring structural dynamics because of its enhanced overall performance.

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Huang, X., G. Lu, and T. X. Yu. "Collapse of square metal tubes in splitting and curling mode." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 1 (2006): 1–13. http://dx.doi.org/10.1243/095440606x78254.

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This paper presents a further investigation into the energy absorbing behaviour of axially splitting and curling square mild steel and aluminium tubes. Both quasi-static and dynamic tests were conducted. A simple quasi-static kinematic model is developed which describes all the main features of the deformation process. It is assumed in this model that cracks start from the four corners and propagate along the axial direction due to continuous fracture/tearing. The free side plates so formed by cracks roll up into four curls with a constant radius. Formulas for the average crush force, curl radius, and the energy absorption are achieved by analysing the ‘far-field’ and ‘near-tip’ deformation events and the bending moment at the crack tip. This quasi-static model is also extended and used for dynamic cases to explore strain-rate effects in splitting square metal tubes. Solutions are presented and detailed comparisons are made between theoretical predictions and experimental results.

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Pavelko, V. "Properties of the crack resistance of layered composite and simulation of a crack quasi-static growth." Journal of Physics: Conference Series 2692, no. 1 (2024): 012015. http://dx.doi.org/10.1088/1742-6596/2692/1/012015.

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Abstract The outcomes of standard test of a carbon/epoxy layered composite using DCB specimen for measuring of the I-mode interlaminar fracture toughness (IFT) were analysed. Using the test results and earlier developed the model of quasi-static growth of crack (delamination) in layered composite, the investigation of variable properties of IFT was continued. It is shown that the use of stationary continuous functions for mathematical description of IFT does not allow to completely satisfy to the data of test. The simplest type of stationary discontinuous function is selected for analysis and simulation: the periodic piecewise-constant function. Using the model of quasi-static growth of crack and the mentioned type of variable IFT function the process of a crack propagation in DCB sample at quasi-static loading with control of displacement is simulated. Comparison of IFT function and the crack resistance (R-curve) together with other outcomes of simulation are the base of proposed procedure of variable IFT estimation from DCB Standard test.

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Szwajka, Krzysztof, Marek Szewczyk, and Tomasz Trzepieciński. "Experimental Compaction of a High-Silica Sand in Quasi-Static Conditions." Materials 16, no. 1 (2022): 28. http://dx.doi.org/10.3390/ma16010028.

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In the compaction process, an uneven densification of the powder through the entire height of the die is a major problem which determines the strength properties of the final product, which vary throughout the entire volume. The aim of this investigation was to determine the distribution of the forming pressure inside the die and to visualise the differences in compaction. To determine the pressure inside the die during the compaction process, the deformation on the die surface was measured by means of strain gauges. However, in order to visualise the densification of high-silica sand during the compaction process, an X-ray tomograph was used, which permits one to visualise the interior of the die. The authors developed an analytical model of how the change in internal pressure influences the change in stresses arising on the outer surface of the die, and, as a result, the friction force. It has been observed that the highest values of pressure as well as the highest concentrations of the loose medium are found closest to the punch and decrease with distance from the punch. Moreover, based on the measurements of deformation, a dependence of the pressure distribution on the value of friction forces was observed, which prompted further analysis of this phenomenon. As a result, tests to determine the coefficient of friction between the die and the loose medium were carried out. This made it possible to describe the pressure distribution inside the die, based on the pressure applied and the height of the die.

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Cui, Haijun, Fanrong Meng, and Ping Yong. "Research on Process and Mechanical Properties of PLA Composites in Melt Deposition Molding Based on Computer Software Analysis." Journal of Physics: Conference Series 2459, no. 1 (2023): 012002. http://dx.doi.org/10.1088/1742-6596/2459/1/012002.

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Abstract Fused deposition polylactic acid (PLA) von berg system materials have been widely used in automotive, aerospace and other fields, and in these areas, inevitably need under static load and dynamic load, so the fused deposition PLA materials under quasi-static and dynamic loading of mechanical properties, establish its parameters such as temperature and strain rate, and constitutive model is related to material performance evaluation and optimization of fused deposition parameters and key for promoting the development of the fused deposition technology.

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Bazhenov, V. G., A. Yu Konstantinov, S. S. Kukanov, D. L. Osetrov, and A. A. Ryabov. "Application of the Experimental-Calculation Approach for Identification of Deformation and Strength Characteristics of Elastic-Plastic Materials under Quasi- Static and Dynamic Loading." PNRPU Mechanics Bulletin, no. 1 (December 15, 2025): 45–58. https://doi.org/10.15593/perm.mech/2025.1.04.

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The paper presents numerical and experimental studies of deformation and fracture processes of 10G2FBU and St35 steels under various types of quasi-static and dynamic loadings: tension of a solid rod and M8 bolts with smooth and threaded working parts, as well as compression of compact cylindrical specimens. The developed experimental-calculation techniques are described in detail and shown schematically for quasi-static and dynamic true strain diagrams in tensile and compression experiments. Application of these techniques made it possible to determine quasi-static and dynamic true strain diagrams for steels 10G2FBU and St35. The obtained quasi-static deformation diagrams of 10G2FBU steel in tension and compression practically coincide. It was found that in the construction of true strain diagrams for 10G2FBU steel, the strain rate at values above 500 1/s has a significant influence. A coupled fracture model based on the kinetic equation of damage accumulation in combination with the strength criterion of the Pisarenko-Lebedev type is proposed and implemented to investigate and describe the deformation and fracture processes of elastoplastic materials. Based on the experimental-calculation approach, a new methodology for fitting material parameters for the proposed fracture model is developed. Accordingly, the material parameters of the coupled fracture model for St35 steel are determined. The results of numerical modeling of the fracture process of M8 bolts with smooth and threaded working part under quasi-static tension show a quantitative and qualitative correspondence of the type and character of fracture with the experiment. The joint application of the experimental-calculation approach and the proposed coupled fracture model allows a more accurate description of the deformation and fracture processes of elastic-plastic materials.

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Journal articles on the topic 'Quasi-static process'

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