Статті в журналах: "Quasi-static process"

1

Kitsunezaki, S., and A. Kurumatani. "The Creation Process of Faults in Quasi-static Deformation." Granular Matter 5, no. 4 (February 1, 2004): 185–92. http://dx.doi.org/10.1007/s10035-003-0150-x.

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2

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 (January 18, 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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3

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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4

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 (April 22, 2021): 1910–17. http://dx.doi.org/10.1021/acssensors.1c00261.

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5

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 (May 24, 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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6

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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7

Zhu, Hongwei, Yaodong Feng, Danfeng Lu, Yahya Sandali, Bin Li, Gang Sun, Ning Zheng, and Qingfan Shi. "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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8

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

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9

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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10

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 (December 2013): 124701. http://dx.doi.org/10.1088/0256-307x/30/12/124701.

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11

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 (August 28, 2020): 5617–29. http://dx.doi.org/10.1007/s00603-020-02231-y.

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12

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 (November 6, 2007): 715–18. http://dx.doi.org/10.1007/s10934-007-9158-7.

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13

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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14

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 (April 1, 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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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 (December 15, 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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16

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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17

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

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18

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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19

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

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20

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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21

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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22

Hamdan, S., W. Dwianto, T. Morooka, and M. Norimoto. "Softening Characteristics of Wet Wood under Quasi Static Loading." Holzforschung 54, no. 5 (September 6, 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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23

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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24

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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25

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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26

FIEDKIEWICZ, Łukasz, and Ireneusz PIELECHA. "Selection of ion sensor operating parameters in quasi-static conditions." Combustion Engines 179, no. 4 (October 1, 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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27

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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28

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 (April 21, 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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29

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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30

Gozdur, Roman. "Study of Quasi-Static Magnetization with the Random-Field Ising Model." Algorithms 13, no. 6 (May 29, 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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31

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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32

Xie, Zong Hong, Qun Yan, Jiang Tian, and Xiao Yu Liu. "Quasi-Static Indentation Test on Composite Sandwich Panels with Foam Core." Advanced Materials Research 718-720 (July 2013): 214–18. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.214.

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In accordance to ASTM test standards, this paper presents experimental studies on quasi-static indentation tests on sandwich panels with carbon fiber reinforced facesheet and foam core. The indentation force vs. displacement curves were obtained. A series of tests with different indentation depth were carried out to study the damage modes and damage propagation process of foam core sandwich panels under quasistatic indentation force.

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33

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 (June 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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34

Shahapurkar, Kiran, Khalid Alblalaihid, Venkatesh Chenrayan, Abdulaziz H. Alghtani, Vineet Tirth, Ali Algahtani, Ibrahim M. Alarifi, and M. C. Kiran. "Quasi-Static Flexural Behavior of Epoxy-Matrix-Reinforced Crump Rubber Composites." Processes 10, no. 5 (May 11, 2022): 956. http://dx.doi.org/10.3390/pr10050956.

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Waste tires have emerged as a severe environmental threat worldwide as they create a number of disposal and landfill burden issues. In the present study, environmental pollutant crump rubber derived from waste discarded tires was reinforced with epoxy resin and prepared by means of an open-mold casting method to assess its mechanical properties. The impact of crump rubber content (0, 10, 20 and 30 vol.%) on the mechanical behavior of the composites was assessed using three-point bending tests at a constant strain rate of 0.1 and 0.01 mm/s. The stress–strain profiles of the 0.01 mm/s specimens revealed higher strains to failure compared with the 0.1 mm/s tested specimens and all the specimens showed brittle failure. Irrespective of the strain rates, tests revealed a marginal increase in the strength values of the composites and a significant increase in the modulus of all the composites compared with neat epoxy specimens. The results suggest that crump rubber can be effectively used in utilitarian composites requiring good flexural modulus and strength properties. Crump rubber epoxy composites with 30 vol.% of crump rubber showed higher modulus and strength compared with neat epoxy and other composites owing to the toughening phase induced by the crump rubber particles. The failure and fracture features of the specimens were analyzed using scanning electron microscopy.

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35

Zhang, Tao, Amgad Salama, Shuyu Sun, and Mohamed F. El-Amin. "Pore network modeling of drainage process in patterned porous media: A quasi-static study." Journal of Computational Science 9 (July 2015): 64–69. http://dx.doi.org/10.1016/j.jocs.2015.04.010.

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36

Kiliclar, Yalin, O. Koray Demir, Ivaylo N. Vladimirov, Lukas Kwiatkowski, Stefanie Reese, and A. Erman Tekkaya. "Application of a viscoplastic material model on a combined quasi-static-electromagnetic forming process." PAMM 13, no. 1 (November 29, 2013): 171–72. http://dx.doi.org/10.1002/pamm.201310081.

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37

Mauko, Anja, Tomáš Fíla, Jan Falta, Petr Koudelka, Václav Rada, Michaela Neuhäuserová, Petr Zlámal, Matej Vesenjak, Ondřej Jiroušek, and Zoran Ren. "Dynamic Deformation Behaviour of Chiral Auxetic Lattices at Low and High Strain-Rates." Metals 11, no. 1 (December 29, 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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38

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 (April 3, 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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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 (October 4, 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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40

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 (August 15, 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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41

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 (January 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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42

Nyström, Jonas L., Per A. Gradin, and Benny Thörnberg. "An experimental study of the chipping process with focus on energy consumption and chipping angles." Nordic Pulp & Paper Research Journal 33, no. 3 (September 25, 2018): 460–67. http://dx.doi.org/10.1515/npprj-2018-3055.

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AbstractA series of chipping experiments were performed under both dynamic and quasi-static conditions in a laboratory wood chipper (dynamic) and in a MTS-servohydraulic testing machine (quasi-static). One aim with the experiments was to investigate the rate dependency of the energy consumption during chipping. Another aim was to try to determine the load per unit knife edge length required to initiate cutting. The experiments were carried out using different combinations of spout and edge angles. It was found that for large edge angles (keeping the spout angle constant at30^\circ) there was a slight rate dependency such that the energy consumption was larger at higher cutting rates which is quite in opposite of what is expected if wood is assumed to be a viscoelastic material. It was also found that to determine the force at initiation of cutting, is not a trivial task. Both Acoustic Emission monitoring and visual inspection was used to this end. The wood species used in this study was pine (Pinus silvestris).

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Yu, Duo Nian, Yuan Wang, and Jun Wei She. "Simulation of Metal Material Quasi-Static Tensile Test Based on ABAQUS." Applied Mechanics and Materials 328 (June 2013): 985–89. http://dx.doi.org/10.4028/www.scientific.net/amm.328.985.

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As the rapid development of metal material science, various kinds of metal materials have emerged. The strain and stress characteristics of materials are prerequisites of its application in the actual production. So it has to take many experiments which will cost a lot of manpower, materials, time and equipments to get the characteristics. In this paper, we simulate the process of a metal material quasi-static tensile test based on ABAQUS to discuss the accuracy of simulation data with experimental data. The simulation data is compared with the quasi-static tensile test data of a new kind of aluminum and the verification of accuracy is based on numerical fitting method.

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González, Alejandro G., Javier A. Diez, and Lou Kondic. "Stability of a liquid ring on a substrate." Journal of Fluid Mechanics 718 (February 8, 2013): 246–79. http://dx.doi.org/10.1017/jfm.2012.607.

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AbstractWe study the stability of a viscous incompressible fluid ring on a partially wetting substrate within the framework of long-wave theory. We discuss the conditions under which a static equilibrium of the ring is possible in the presence of contact angle hysteresis. A linear stability analysis (LSA) of this equilibrium solution is carried out by using a slip model to account for the contact line divergence. The LSA provides specific predictions regarding the evolution of unstable modes. In order to describe the evolution of the ring for longer times, a quasi-static approximation is implemented. This approach assumes a quasi-static evolution and takes into account the concomitant variation of the instantaneous growth rates of the modes responsible for either collapse of the ring into a single central drop or breakup into a number of droplets along the ring periphery. We compare the results of the LSA and the quasi-static model approach with those obtained from nonlinear numerical simulations using a complementary disjoining pressure model. We find remarkably good agreement between the predictions of the two models regarding the expected number of drops forming during the breakup process.

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45

Gousheva, M., D. Danov, P. Hristov, and M. Matova. "Quasi-static electric fields phenomena in the ionosphere associated with pre- and post earthquake effects." Natural Hazards and Earth System Sciences 8, no. 1 (February 21, 2008): 101–7. http://dx.doi.org/10.5194/nhess-8-101-2008.

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Abstract. To prove a direct relationship between the quasi-static electric field disturbances and seismic activity is a difficult, but actual task of the modern ionosphere physics. This paper presents new results on the processing and analysis of the quasi-static electric field in the upper ionosphere (h=800–900 km) observed from the satellite INTERCOSMOS-BULGARIA-1300 over earthquakes' source regions (seismic data of World Data Center, Denver, Colorado, USA). Present research focuses on three main areas (i) development of methodology of satellite and seismic data selecting, (ii) data processing and observations of the quasi-static electric field (iii) study and accumulation of statistics of possible connection between anomalous vertical electric fields penetrating from the earthquake zone into the ionosphere, and seismic activity. The most appropriate data (for satellite orbits above sources of forthcoming or just happened seismic events) have been selected from more than 250 investigated cases.The increase of about 5-10-15 mV/m in the vertical component of the quasi-static electric field observed by INTERCOSMOS-BULGARIA-1300 during seismic activity over Southern Ocean, Greenland Sea, South-Weat Pacific Ocean, Indian Ocean, Central America, South-East Pacific Ocean, Malay Archipelago regions are presented. These anomalies, as phenomena accompanying the seismogenic process, can be considered eventually as possible pre-, co- (coeval to) and post-earthquake effects in the ionosphere.

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46

Shams, Reza, Abbas Niknejad, Abdul Ghani Olabi, and Mohammad Zamani Nejad. "Quasi-static flattening energy absorption process on preformed circular tubes by numerical and experimental analyses." Thin-Walled Structures 144 (November 2019): 106260. http://dx.doi.org/10.1016/j.tws.2019.106260.

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47

Li, Chunfeng, Dahai Liu, Haiping Yu, and Zhengbo Ji. "Research on formability of 5052 aluminum alloy sheet in a quasi-static–dynamic tensile process." International Journal of Machine Tools and Manufacture 49, no. 2 (February 2009): 117–24. http://dx.doi.org/10.1016/j.ijmachtools.2008.10.006.

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48

Othman, A., A. A. Arifin, S. Abdullah, A. K. Ariffin, and N. A. N. Mohamed. "Analysis of Crushing Laminated Composite Square Tubes under Quasi-Static Loading." Applied Mechanics and Materials 446-447 (November 2013): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.113.

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This paper present on discusses the effect of crashworthiness parameters on pultrusion and hybrid laminated composite square tubes via experimentally. The wall-thicknesses of 2.1 for pultrusion and 1.6 mm aluminum wrap 1 layered were examined at the material fiber type of E-glass reinforced polyester resin of square cross-section subjected to axial quasi-static loading. Comparison has been made for both of type of composite material. During experimental observation, some of crushing modes on stages were identified as initial peak load stage, progressive crushing stage and compaction zone stage. The effects of crushing parameters and failure modes were analyzed and discussed. Results showed that the tubes energy absorption capability was affected significantly by varying of different type of composite in terms of composite fabrication and variable aspect of cross-section. It is also found that different type of fabrication on different manufacturing process of composite reveal in terms of internal energy during crushed events.

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Streicher, Maximilian, Andreas Kortenhaus, Vincent Gruwez, Bas Hofland, Xuexue Chen, Steven A. Hughes, and Matthias Hirt. "PREDICTION OF DYNAMIC AND QUASI-STATIC IMPACTS ON VERTICAL SEA WALLS CAUSED BY AN OVERTOPPED BORE." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 28. http://dx.doi.org/10.9753/icce.v36.papers.28.

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This study comprises a detailed description of the individual overtopped bore impact processes against a vertical wall, situated on top of a dike. A twin peak force impact signal shape was observed with two distinct peaks during every impact. The two peaks were assigned consecutively to the dynamic components (thickness and velocity) or hydrostatic components (run-up of water at the wall) of the impacting bore. The two peaks were termed dynamic F1 and quasi-static F2 impact respectively. Based on available literature semi-empirical equations to describe either the dynamic F1 or quasi-static F2 impact force were investigated and the prediction accuracy evaluated using impact force data from large-scale experiments. The prediction accuracy of the dynamic F1 impacts was very low. The prediction accuracy of the quasi-static impact F2 was increased based on fitting the hydrostatic theory to the maximum run-up measurement at the wall. Based on these findings 80% of the maximum run-up height was effectively contributing to the maximum quasi-static force F2 on the wall. The results coincided well with previous small-scale studies (Chen et al. 2012). After deconstructing the process chain preceding an impact, using the physically most meaningful parameters to predict the impact force, evaluating on a range of existing approaches, and observing the scattered prediction results, it was concluded that the impact behavior is highly stochastic and statistical analysis would be more beneficial.

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Sugimoto, D., A. Sasaki, and T. Ebisuzaki. "Quasi-Static and Steady-State Pictures for Collapsing Core of Type II Supernova." International Astronomical Union Colloquium 108 (1988): 420–21. http://dx.doi.org/10.1017/s0252921100094227.

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Explosion of type II supernova is, in principle, a difficult process: The presupernova star was in gravitationally bound state with negative energy but it has to be divided into two parts, the collapsed core of still lower (negative) energy and the ejected envelope of positive energy. This process is against nature in the sense most of the phenomena in nature proceed towards equipartition of energies. Thus, some finely tuned mechanism should be necessary for successful explosion. Two different mechanisms have been proposed; one is the prompt explosion where the gravitational energy release by the core collapse is transferred to the mantle by a shock wave, and the other is delayed explosion where it is transferred slowly by neutrinos diffusing out of the core. In what follows we shall concentrate in the case of the delayed explosion.

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