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In order to accurately test the mechanical properties of Q420 steel under static tensile conditions, a universal testing machine is used to conduct room temperature static tensile tests on Q420 steel at different strain rates of $0.0001{\mathrm{\text{s}}}^{-1}$, $0.001{\mathrm{\text{s}}}^{-1}$ and $0.01{\mathrm{\text{s}}}^{-1}$. The corrected constitutive model is substituted into ABAQUS software for tensile finite element simulation analysis. The accuracy of Esmaeily-Ghasemabadi (E-G), Hollomon, Swift and Voce empirical constitutive models was evaluated based on the stress–strain curve. The Hollomon model with small error and the Voce model with a large fitting proportion and relatively stable error were selected, combined with strain rate sensitivity functions from Power law, Wagoner and Johnson–Cook/Modified (J-C/M) models for modification. The quantitative analysis has verified that the modified model combining the Power law model with the Voce model was optimal. The correlation coefficient ($R$) of the Voce-Power (V-P) model before necking was consistently 1, and the average absolute relative error ($e_{\mathrm{\text{ARRE}}}$) had decreased to $0.095\%$. The modified V-P model could reliably describe the stress–strain behavior of bcc structure metals. The error of mechanical strength value between calculation and experiment was within $0.4\%$ during the strengthening stage, and the average $e_{\mathrm{\text{ARRE}}}$ of curve fitting was $0.734\%$. This work held great significance for accurately predicting the mechanical properties of Q420 steel in different load conditions, optimizing structural design and ensuring engineering safety. In particular, it was crucial for establishing accurate stress–strain responses in the fatigue life simulation process of wind turbine towers.

The sensitivity of the flow stress of polymers to strain-rate is one of the major concerns in mechanics of materials since polymers and polymer matrix composites are widely used in many engineering applications. In this paper, we present tests on Nylon 6 and Nylon 66 on wide range of strain-rates (0.001-5000s⁻¹). Specifically, we used INSTRON machine for low strain-rates. The high strain-rate measurements were inferred from the Hopkinson bar tests. Only the compressive behaviour was investigated. To eliminate any interference with temperature and humidity effects, test samples were conditioned at 20°C and 50% of hygrometry. Moreover, the effects of the specimen geometry were considered. The current study results are also compared to values found in literature.

The tensile stress-strain curves of iron and a variety of steels, covering a wide range of strength level, over a wide strain rate range on the order of 10⁻³ ~ 10³s⁻¹, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the strain rate sensitivity of the flow stress for the large strain region, including the viscous term at high strain rates, the true fracture strength and the true fracture strain were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide strain rate range.

Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications under impact loading. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation to a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact or shock loading conditions. Results were compared with those of spherical indentation under quasi-static and impact loading and were discussed. The interface bonded specimen method was adopted in order to observe the subsurface damage, especially the formation of shear bands induced during indentation under different loading conditions.

This paper is to understand and model the thermomechanical response of the rotary forged WHA, uniaxial compression and tension tests are performed on cylindrical samples, using a material testing machines and the split Hopkinson bar technique. True strains exceeding 40% are achieved in these tests over the range of strain rates from 0.001/s to about 7,000/s, and at initial temperatures from 77K to 1,073K. The results show: 1) the WHA displays a pronounced changing orientation due to mechanical processing, that is, the material is inhomogeneous along the section; 2) the dynamic strain aging occurs at temperatures over 700K and in a strain rate of 10^-3 1/s; 3) failure strains decrease with increasing strain rate under uniaxial tension, it is about 1.2% at a strain rate of 1,000 1/s; and 4) flow stress of WHA strongly depends on temperatures and strain rates. Finally, based on the mechanism of dislocation motion, the parameters of a physically-based model are estimated by the experimental results. A good agreement between the modeling prediction and experiments was obtained.

The high-temperature deformation and damage behavior of ultrafine-grained (UFG) Cu produced by equal channel angular pressing (ECAP) were investigated and compared at two strain rates of 10^-2 s^-1 and 10^-3 s^-1. It is found that the strain rate has an obvious effect on the deformation and damage behavior of UFG Cu, especially at the testing temperatures near and above recrystallization. In general, the lower the strain rate, more universally grain coarsening takes place, the lower the yield stress and steady flow stress are, and more aggravated the degree of deformation damage becomes.

By means of finite element method, the effect of velocity of balls on the strain and stress of low carbon steel surface layer during the course of surface mechanical attrition treatment (SMAT) are investigated. The effect of different impact velocity on strain rate and grain refinement mechanism is also analyzed. Calculation results confirm that there exists severe plastic deformation in the surface layer: strain, strain rate and stress gradually decrease along the depth of the treated sample during SMAT, which is in agreement with the microstructures observed in corresponding locations. Strain and strain rate play an important role in the grain refinement process and the resultant grain sizes upon plastic deformation.

Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10${}^{-2}$ s${}^{-1}$ led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10${}^{-3}$ s${}^{-1}$, indicating a typical brittle fracture mode. When the strain rate is 10${}^{-2}$ or 10${}^{-1}$ s${}^{-1}$, a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

Cr coating on Zr-based fuel tubes is a potential approach for the development of accident tolerant fuels (ATF). To settle the cracking behavior and quantitative evaluation of shear strength of Cr coating under different loading conditions, the average shear strength between Cr coating and zircaloy substrate has been estimated using a modified shear-lag model in this paper. Its key parameters are determined experimentally, and the tensile method has been used to research the cracking behavior of Cr coating under different strain rates. The results show that with the increase of strain rate, the interfacial shear strength increases because of the decrease of cracking spacing, while the shear strength changes erratically with the coating thickness increases. Furthermore, abundant two unequal-crack-spacings and few two equal-crack-spacings are observed which are perpendicular to the loading direction.

This study investigated the effects of Nb addition on the glass formation ability, mechanical properties, and microstructural evolution of Fe–Y–B bulk metallic glass (BMG) alloys. The glass formation ability of the alloys with different Nb contents was evaluated by means of X-ray diffraction and differential scanning calorimetry. The mechanical properties of the various BMGs were examined using a universal testing machine (MTS 810) under quasi-static strain rates of 10${}^{-3}$–10${}^{-1}$ s${}^{-1}$. The high strain rate mechanical properties of the BMGs were tested using a split Hopkinson pressure bar system under strain rates of $2\times 10^3$ to $4\times 10^3$ s${}^{-1}$. Finally, the microstructures of the fracture surfaces of the alloys tested at different strain rates were observed by scanning electron microscopy (SEM).

In this study, the alloys used contained Co, Cr, Fe, Ni, and V as the primary elements, while 6%–10% Cu was used as the added element. The high-entropy alloys (HEAs) were made in an electric-arc vacuum furnace from which specimens in the form of cylinders with a 5-mm diameter and 5-mm length were fabricated. An XRD analysis revealed that alloys with 6% and 8% Cu had a single-phase FCC structure, and a weak BCC peak only appeared in the (110) direction in alloys with 10% Cu. A universal testing machine was used for testing at the strain rates of $1\times 10^{-1}$${\text{s}}^{-1}$, $1\times 10^{-2}$${\text{s}}^{-1}$, and $1\times 10^{-3}$${\text{s}}^{-1}$, and the high strain rate was tested using a split Hopkinson pressure bar (SHPB) under strain at 3000${\text{s}}^{-1}$, 4000${\text{s}}^{-1}$, and 5000${\text{s}}^{-1}$, respectively. The specimens did not fracture during the quasi-static compression and dynamic impact tests, which displayed better ductility. The surface of the three alloys had extensive dendrites and non-equiaxed crystal structures. In an EDS composition analysis, the Cr and V elements were more frequently observed in the intergranular region than in the interdendritic region.

In reality, railway prestressed concrete sleepers frequently experience significant aggressive loading conditions and harsh environments. Especially in sharp curves, lateral loading of train wheels in combination with incompressible hydraulic pressure aggravates the lateral oscillation and abrades the surface of sleepers right underneath the rail seats. Many investigators in the past have proposed various material models to improve abrasive resistance characteristics, but those have been mostly applied to the new products using novel materials such as fiber-reinforced concrete. On the other hand, prestressed concrete sleepers have been used for over 50 years and they have become worn over time. This paper highlights the dynamic capacity evaluation of worn sleepers, which will lead to predictive models that could be realistically applied to asset management of railway lines. This paper presents an investigation into the structural capacity reduction in worn railway prestressed concrete sleepers considering the effects of strain rate and loss of prestressing steel. RESPONSE2000 has been used to evaluate the residual dynamic capacity based on the modified compression field theory. Unprecedented parametric studies have been carried out to determine the influences of uniform and gradient prestress losses on prestressed concrete capacity. The study results exhibit the level of wear and tear, which is critical to the dynamic integrity of sleepers required for immediate replacement. The outcome of this study will help improve the practical maintenance and monitoring technology in railway industry.

Numerical simulations were conducted to validate computational and constitutive models for steel materials through dynamic material tests involving both tension and compression. These simulations involved the numerical modeling of the split Hopkinson pressure bar (SHPB) apparatus, with the appropriate loading applied directly in compression and indirectly in tension. To induce a tensile wave within the specimen, a shoulder, such as a coupler or collar, was interposed between the bars. The simulations were carried out using the LS-DYNA finite element code. In these numerical simulations of the SHPB tests, the MAT-15 Johnson–Cook material model was applied to represent mild steel. The resulting stress–strain relationships obtained under both compression and tension conditions were subsequently compared to corresponding experimental data. The primary objectives of these simulations were to determine the optimal placement of strain gauges on both the input and output bars of the tensile SHPB setup. Additionally, the simulations aimed to assess the influence of the gauge length-to-diameter ratio on the behavior of the mild steel specimen subjected to dynamic tension and compression. The results showed that the pulse produced due to the mechanical mismatch of the element at boundaries can be avoided using the length of the input bar smaller than the output bar. Further, the location of the strain gauge in the case of the output bar should be toward the output bar-shoulder interface, while in the case of the input bar, it should be considered at the center of the span of the bar.

To investigate the effect of viscoelastic behavior on instantaneous muscle mechanics, the passive mechanical properties for the range of physiologically relevant rates should be clarified. Therefore, a series of uniaxial extension tests were conducted at various stretching rates using the muscle fiber bundles, which contained extracellular matrix (ECM) and interfibrillar microstructural components. We revealed that the tensile strength is strain rate-sensitive over the examined range, i.e., the muscle fiber bundle failed at 109$\pm$34, 122$\pm$44, and 179$\pm$61kPa (mean$\pm$SD) for strain rates of 0.02, 0.1, and 0.5s${}^{-1}$, respectively. Moreover, we found that the applied stretch was not distributed uniformly even in relaxed conditions; the ratio between maximum and minimum local strains within a specimen was 2–3 on average during stretching and increased up to approximately four just before failure, indicating local mechanical heterogeneity along a fiber bundle and its exaggeration by stretching. Macroscopically, however, the tensile strain at failure was almost constant, $\sim$50%. The local heterogeneity of muscle strain distribution can lead to unstable oscillation in a computational model. Thus, in addition to the intrinsic viscous effects of the muscle fiber itself, those of ECM and interfibrillar microstructural components should be considered in mathematical modeling of skeletal muscle.

Modeling the mechanical behavior of bone is very complex due to substantial variability of the mechanical response of bone. The objective of this study is to investigate the link between morphology of the human parietal bone and its mechanical behavior in compression with two different strain rates. Five formalin-preserved human skulls were used, and 10 specimens were taken from the parietal bone of each subject. The internal geometry of the osseous material was studied with a micro-tomography device. For mechanical testing, quasi-static (0.02 s^–1) tests on a conventional compression machine and dynamic tests (1500 s^–1) on a split Hopkinson pressure bar (SHPB) were conducted on 9 mm diameter samples. The results were used to examine relationships between the morphological parameters to find morphological correlations. Linkages between mechanical behavior and morphology of the human parietal bone were also analyzed to develop a behavior model based on micro-structure parameters as determined by micro-scanning.

The meniscus is a multifunctional fibrocartilage tissue in the knee joint which stables joint movement, bears load and absorbs impact. Improper collisions will cause damage to meniscus tissue and lose its original functionality. However, it is difficult to fully evaluate the mechanical properties of the meniscus based on static test results alone. In this study, Split Hopkinson Pressure Bar (SHPB) and hydraulic material testing system (MTS) were utilized to examine the quasi-static and dynamic properties of the porcine meniscus along with two different orientations. The results showed that the meniscus is a strain rate sensitive material and its mechanical properties mainly depend on the orientation of collagen fiber bundles in the peripheral direction. The meniscus tissue did not show obvious yield characteristics under quasi-static test conditions. However, the meniscus showed clear yield behavior under dynamic loading. When the strain rate increased, the elastic modulus of the radial meniscus remained around 35 MPa while the elastic modulus of the axial meniscus increased from 30 MPa to 80 MPa. This study demonstrates that the meniscus is sensitive to strain rate at both dynamic and quasi-static conditions, and the meniscus is an anisotropic biological tissue.

The quasi-static and dynamic compression responses and failure of fiber-reinforced syntactic foams were investigated. The role of fiber volume fraction on the compression response of syntactic foams was examined in terms of mechanical behavior and energy absorption under both quasi-static and dynamic conditions. Results showed that the mechanical behavior and energy absorption of the reinforced specimens increased with increasing fiber volume fraction. The syntactic foams exhibited distinct strain rate sensitivity; and their yield strength and elastic modulus increased by 41.1% and 85.1%, respectively, as strain rate increased from 0.0011 s${}^{\mathrm{\text{-1}}}$ to 1070 s${}^{\mathrm{\text{-1}}}$. The deformation and failure processes of the syntactic foams were also examined, and the underlying mechanisms were discussed.

The polymer yield behavior is affected by temperature, strain rate and pressure. In this work, tensile yield stress of polyetheretherketone (PEEK) is characterized for temperature ranging between $223^{\circ }\mathrm{\text{K}}$ and $433^{\circ }\mathrm{\text{K}}$ ($-50^{\circ }$C and $160^{\circ }$C). The tensile yield stress is decreasing in terms of temperature. Two temperature transitions are observed: $320^{\circ }\mathrm{\text{K}}$ ($\sim 37^{\circ }$C) and the glass transition temperature. The temperature sensitivity is well captured by the modified-Eyring equation proposed by the authors. This paper completes three previous works where the PEEK’s yield behavior was described under compression on wide ranges of strain rate and temperature and under tension on a wide range of strain rates. Thus, the pressure effect is analyzed in terms of temperature and strain rate. Using either the experimental data or the modified-Eyring equation, the effect of the hydrostatic pressure is increasing with temperature and decreasing with strain rate.

The mechanical properties of graphene oxide (GO) during tensile fracture were studied using molecular dynamics methods, and the influence of hydroxyl and epoxy groups on the mechanical properties of GO was explored. In addition, the changes in mechanical properties of GO under different temperatures and strain rates were studied to gain a deeper understanding of its mechanical behavior. The results indicate that hydroxyl and epoxy groups have a significant influence on the elastic modulus, ultimate stress, and ultimate strain of GO. The presence of hydroxyl and epoxy groups can alter the molecular structure of GO, thereby affecting its ultimate stress and strain. When the number of hydroxyl groups is 16 and the number of epoxy groups is 20, the ultimate stress decreases by about 31% and the elastic modulus decreases by about 20%. The variation of elastic modulus, ultimate stress, and ultimate strain of GO with temperature was studied at three temperatures: 300K, 500K, and 800K. As the temperature increases, the amplitude of atomic vibration increases and internal defects and cracks in GO continue to form and expand. At the same time, its coefficient of thermal expansion also increases, causing deformation and loosening of the crystal structure, resulting in a decrease of about 10% in the ultimate stress of GO, and a slight decrease in the ultimate strain and elastic modulus. Finally, the influence of different strain rates on the mechanical properties of GO was studied. As the strain rate increases, the intermolecular interactions within GO are rapidly altered, and the previously loose structure gradually becomes tightly ordered, resulting in an increasing trend in the elastic modulus, ultimate stress, and ultimate strain of GO.

Materials that characteristically respond to mechanical stimulus are utilized in a wide variety of engineering applications as strain gauges. The response can be produced as a change in resistance or a change in capacitance. Constantan was initially utilized in strain gauges and exhibited a gauge factor (GF) of 2. With the development of fabrication techniques, new materials are correspondingly utilized in strain gauges that revealed a GF higher than 2. However, a review pertaining to the latest materials utilized in strain gauges is absent. Therefore, in this review article, strain gauges utilizing metallic, polymer, and ceramic-based materials were investigated by evaluating their fabrication method, characterization in numerous testing conditions, gauging their sensitivity and the parameters influencing the same, and proposing a real-world biomedical application based on the sensor properties ranging from monitoring of orthopedics, knee laxity, heartbeat, and mechanical properties of implants and prosthetics, to stretchable and wearable sensors for e-skin and exoskeletons.