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Rubber-like materials such as sealant with recent developments in formulation are widely used in various structural components, especially in aerospace industry with many applications such as the sealing of bolted joints on aircraft. The objective of this paper is to assess the load transfer distribution in bolted-sealed joints through an approach coupling both experimental and numerical tests. Quasi-static and relaxation tests under uniaxial and pure shear loading were carried out to determine the parameters of phenomenological hyperelastic laws and of the generalized Maxwell model for the sealant PR 1782 C2. The fastener is an alloy steel bolt with a protruding head when the substrates are made from aluminum 2024-T3. Experimental and numerical quasi-static tests were then performed on double-lap bonded and bolted-sealed joints under in-plane loading. The numerical tests are done using 2D and 3D Finite Element (FE) models; they involve the visco-hyperelastic behavior previously assessed for the sealant. Accounting for visco-hyperelasticity makes it possible to better estimate the load transfer between bolt and sealant layer. Typically, the bolt load transfer rate is derived from numerical output for different sealant thicknesses. In the considered geometrical joint configuration, the sealant load contribution is between 7% and 13% according to the sealant thickness. Methodology and results provide a solid basis for the fatigue strength prediction of bolted-sealed joints. [ABSTRACT FROM AUTHOR]

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test. [ABSTRACT FROM AUTHOR]

Gauge length influences the biomechanical properties of herbaceous roots such as tensile resistance, tensile strength and Young's modulus. However, the extent to which and how these biomechanical properties of herbaceous roots are influenced remain unknown. To better understand the behavior of roots in tension under different conditions and to illustrate these behaviors, uniaxial tensile tests were conducted on the Poa araratica roots as the gauge length increased from 20 mm to 80 mm. Subsequently, ANOVA was used to test the impact of the significant influences of gauge length on the biomechanical properties, nonlinear regression was applied to establish the variation in the biomechanical properties with gauge length to answer the question of the extent to which the biomechanical properties are influenced, and Weibull models were subsequently introduced to illustrate how the biomechanical properties are influenced by gauge length. The results reveal that (1) the variation in biomechanical properties with root diameter depends on both the gauge length and the properties themselves; (2) the gauge length significantly impacts most of the biomechanical properties; (3) the tensile resistance, tensile strength, and tensile strain at cracks decrease as the gauge length increases, with values decreasing by 20%–300%, while Young's modulus exhibits the opposite trend, with a corresponding increase of 30%; and (4) the Weibull distribution is suitable for describing the probability distribution of these biomechanical properties; the Weibull modulus for both tensile resistance and tensile strain at cracks linearly decrease with gauge length, whereas those for tensile strength and Young's modulus exhibit the opposite trend. The tensile resistance, tensile strength, and tensile strain at the cracks linearly decrease with increasing gauge length, while the tensile strength and Young's modulus linearly increase with increasing gauge length. [ABSTRACT FROM AUTHOR]

The hydraulic bulge test with micro-samples is expected to be useful in the damage assessment of long-service-period metals to understand the degeneration of their mechanical properties. Since the hydraulic bulge test has a different stress state from the classical uniaxial tensile test, we need to understand their correlation and differences. In this study, the hydraulic bulge test and the uniaxial tensile test are employed to analyze the mechanical properties of three typical metals used in pressure vessels: 316L, 16MnDR, and Q345R. By utilizing Kruglov's vertex thickness and Panknin's curvature radius equivalent, the pressure–displacement curves from the hydraulic bulge test are converted into biaxial stress–strain curves. Based on the equivalent plastic energy model, the biaxial stress–strain curves are converted into uniaxial stress–strain curves with an error less than 10% in the strain hardening stage, achieving the unified characterization of mechanical properties under different stress states. Moreover, the hydraulic bulge test provides a more extensive strain hardening stage, and the fracture strains are 9–16.5% larger than those of uniaxial tensile test. This paper provides a reference for using the hydraulic bulge test with micro-samples in studying the mechanical properties and presents the advantages of this novel test method. [ABSTRACT FROM AUTHOR]

The tensile strength of clay is an important factor in determining the stability of soil slope. Due to the fragmentation of soil, the understanding of the tensile strength of clay is not clear. In this study, the uniaxial tensile test of remolded clay is carried out to analyze the influence of water content and tensile rate on the tensile strength of remolded clay based on the self-designed direct tensile test device. The test results show that: (1) The tensile strength of remolded clay increases first and then decreases with the increase of water content, as the other conditions (such as tensile rate) remain stable. The peak tensile strength occurs near the optimal water content. (2) The tensile strength of remolded clay increases with the increase of tensile rate, as other conditions such as water content remain unchanged. (3) In the water content range (18%–24%) of this study, the remolded clay undergoes plastic deformation under uniaxial tension, and shows softening failure law after reaching the peak tensile strength. (4) The discrete element simulation method is used to analyze and verify the results obtained from the above experiments. The results of this study can be used for the stability analysis of soil slope and the calculation and design of slope protection.

Seven groups of uniaxial tensile experiments on wood plastic composites with a High Density Polyethylene (HDPE) matrix at different temperatures were completed in this paper. The test temperatures ranged from -60 °C to 60 °C, with a temperature difference of 20 °C for each group. All samples exhibited tensile brittle fracture. The test results showed that the tensile strength of the specimens decreased continuously with increasing temperature. Taking 0 °C as the reference temperature, the ultimate strength of the sample at -60 °C was 1.63 times that at 0 °C. When the temperature was 60 °C, this value was 0.41. Then, it can be calculated that the ratio of the strength of the sample at -60 °C to that at 60 °C was approximately 3.93, and the corresponding ratio of the elastic modulus was approximately 4.52. This shows that the mechanical properties of WPC are sensitive to changes in temperature. The variation coefficient of the average strength and elastic modulus of WPC for different specimens at different temperatures was less than 0.17, showing good stability due to the small dispersion of mechanical properties among different samples at any specific temperature.

Based on the rate-dependent non-aging constitutive model and the rate-independent aging constitutive model, a rate-dependent aging constitutive model is proposed to explain the changes in mechanical properties of ethylene propylene diene monomer (EPDM) rubber under different strain rates and aging states. In order to simulate the actual use state of rubber, accelerated aging tests are conducted on the samples in a hot air aging environment. The grey wolf algorithm is utilized to accurately fit the engineering stress–strain curve obtained from the experiment, obtaining specific coefficient values that represent the effects of strain rate, aging time, and aging temperature in the constitutive model. The results confirm the effectiveness of the proposed rate-dependent aging constitutive model in accurately predicting the mechanical property changes of EPDM rubber under different strain rates and aging states. The consistency between the experimental data and the calculated results is within the acceptable error range. It is worth noting that the stress in the model shows the dependence on strain rate, aging time and aging temperature, emphasizing the mechanical property changes of EPDM rubber at high temperatures and low strain rates simulated in the uniaxial tensile state. [ABSTRACT FROM AUTHOR]

The correlation between strain rates and the mechanical properties of HTPB propellant with 90% solid content (mass fraction) was investigated by uniaxial tensile tests at different tensile rates, and the tensile fracture surface was observed by scanning electron microscope (SEM). The effects of strain rate on the mechanical properties and failure mechanisms of the propellant were analyzed. The results show that the stress--strain curve of the propellant appears an arc segment phenomenon at low tensile rates. With the increase of tensile rates, the stress--strain curves of propellant gradually changes from 5 segment to 4 segment. The initial modulus and the maximum tensile strength of the propellant show an increasing trend with an increase in the tensile rates. The maximum elongation of the propellant decreases with an increase in the strain rate, and the maximum elongation of propellant is only 33.9% when the strain rate is 1 190.48 X 10 4s 1 . With the increase of strain rate, the failure mechanism of propellant gradually changes from particle dehumidification to matrix tearing, without particle fragmentation. [ABSTRACT FROM AUTHOR]

The present study used polymers such as PLA and ABS filaments for the 3D printing parts with varying layer thicknesses. The mechanical properties and surface finish of the as-printed and epoxy resin-coated samples were investigated. Noteworthy findings indicate that when the PLA material is printed at a layer thickness of 0.06 mm followed by no coating one can achieve superior tensile strength of approximately 39 MPa as compared to 20 MPa of ABS material. The ultimate tensile strength of the coated materials averaged approximately 15 MPa for both PLA and ABS. The surface roughness of PLA material printed with a 0.06 mm layer thickness showed a 95.13 % reduction after coating. Despite ABS samples being harder than PLA material, the layer thickness emerged as the most influential factor in enhancing the hardness. The dominance of lower layer thickness over other conditions is particularly evident in the modulus of elasticity. In addition to the experimental investigation, a non-linear structural analysis of the uniaxial tensile behaviour of the coated and uncoated 3D prints was also carried out. The fracture modes and deformation behaviours in numerical modelling and experimental results across various parametric conditions were found to be in good agreement. Specifically, the numerical results at lower loading conditions for a layer thickness of 0.06 mm PLA and ABS samples, in the uncoated conditions, mirrored the experimental outcomes.

A new Mg-4Zn X Ti-6Al-4V (TC4, of 0, 1, and 3 wt.%) alloy was successfully fabricated by a simple and low-cost gravity casting method and heat treatment at 150 °C for 24 h. The composite was examined by XRD, uniaxial tests, FESEM/EDS, potentiostat/EIS, and immersion tests for the material's microstructures, mechanical properties, electrochemical characteristics, and corrosion resistance. Experimental results indicate that heat treatment enables the precipitation of Zn along the Mg grain boundaries and drives the co-precipitation of Al around the TC4 particles and nearby grain boundaries. Uniaxial tensile tests reveal that TC4 reinforces the Mg-Zn matrix material with higher elastic modulus, ultimate tensile stress, and toughness. The heat treatment further enhanced these mechanical properties. Electrochemical tests show that 1 wt.% TC4 composite exhibits the highest open circuit potential among all tested samples, which implies the 1 wt.% TC4-added Mg-Zn is better resistant to the oxidation of the essential metals Mg, Zn, and Al. The immersion tests in the HBSS solution further show that the 1 wt.% TC4 composite has the lowest rise of pH values after 14 days, and EDS for the corroded surface signifies that Mg is the main element vulnerable to oxidation by corrosion. [ABSTRACT FROM AUTHOR]

Shape memory alloys (SMAs) demonstrate a shape memory effect and superelasticity that can provide recovery performance to structural members. In this study, a round SMA bar was designed to replace the conventional deformed steel bar, particularly within the plastic hinge section of structural members. To integrate the SMA bar and the existing steel bar, a mechanical coupler was proposed by utilizing the advantages of both one-touch and threaded couplers. Uniaxial tensile tests were conducted to analyze the performance of the proposed coupler and the mechanical properties of the SMA–steel connected bar. Stress and strain relationships were examined for steel bars mechanically connected with the SMA bar and for SMA bars before and after exhibiting the shape memory effect. To induce the shape memory effect, SMA should be heated above the finished austenite temperature. Due to the difficulty of accurately measuring strain on the heated bar using traditional contact methods, we employed digital image correlation technology for precise strain measurement of the heated SMA bar. The experimental results indicate the effective application of SMA bars within the plastic hinge region of structural members using the proposed mechanical coupler. [ABSTRACT FROM AUTHOR]

Modern materials mostly exhibit a low formability or a complex material behavior. For example, the common mild steel DC06 exhibits a strain state dependency in the yield stress and a strain dependency of the Lankford coefficients. Thus it is necessary to characterize the material properties from the onset of plastic deformation up to fracture. For example in the uniaxial tensile test, the flow stress and the r -values can be determined. According to the standards, the characterization is only applicable up to uniform elongation. In the case of DC06, the uniform elongation is with 24% comparatively low in contrast to the ultimate elongation with 60%. Research has proven, that the true stress can be characterized up to high strain in the uniaxial tensile test. For the strain dependent Lankford coefficient, this validation is missing. The aim in this investigation is the analysis of the strain dependent anisotropy up to high strain levels in uniaxial tensile tests and the validation. This is done with a comparison of optically measured r -values with the grain structure evolution of the pre stretched parts. These results prove the applicability of the standardized evaluation of Lankford coefficients out of DIC data above the uniform elongation. [ABSTRACT FROM AUTHOR]

In this paper, an experimental and theoretical study on the uniaxial tensile behavior of a fiber-reinforced polymer (FRP) grid-engineered cementitious composite (ECC) composite layer is described. Based on the test parameters, including the ECC material properties, the ECC cross-sectional area and the FRP grid cross-sectional area, three groups of ECC specimens and six groups of composite layer specimens were tested to reveal their joint action mechanism and tensile behavior. The experimental results showed two failure modes: fibers were pulled off or pulled out in the ECC specimens, and in the composite layer specimens, part of the fiber bars in the FRP grid was pulled off. The stress–strain curves show three stages: the elastic stage, softening stage and hardening stage. Due to the reinforcement of the FRP grid, the ultimate stress of the composite layer increased significantly compared with that of the ECC specimens. The composite layer softening strain was primarily related to the ECC softening strain, and the ultimate strain was primarily related to the FRP grid fracture strain. Moreover, a three-stage model was proposed to predict the stressstrain relationship, exhibiting a higher prediction accuracy and smaller dispersion compared with the three existing models.

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test.

The hydraulic bulge test with micro-samples is expected to be useful in the damage assessment of long-service-period metals to understand the degeneration of their mechanical properties. Since the hydraulic bulge test has a different stress state from the classical uniaxial tensile test, we need to understand their correlation and differences. In this study, the hydraulic bulge test and the uniaxial tensile test are employed to analyze the mechanical properties of three typical metals used in pressure vessels: 316L, 16MnDR, and Q345R. By utilizing Kruglov’s vertex thickness and Panknin’s curvature radius equivalent, the pressure–displacement curves from the hydraulic bulge test are converted into biaxial stress–strain curves. Based on the equivalent plastic energy model, the biaxial stress–strain curves are converted into uniaxial stress–strain curves with an error less than 10% in the strain hardening stage, achieving the unified characterization of mechanical properties under different stress states. Moreover, the hydraulic bulge test provides a more extensive strain hardening stage, and the fracture strains are 9–16.5% larger than those of uniaxial tensile test. This paper provides a reference for using the hydraulic bulge test with micro-samples in studying the mechanical properties and presents the advantages of this novel test method.

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Wire arc additive manufacturing is considered to allow a reduced material consumption for structural steel components by efficiently distributing the material only where necessary. Parts produced with this technology exhibit an irregular, imperfect geometry, which influences their structural behaviour. This paper describes a dataset, which includes geometry information for point-by-point wire arc additively manufactured steel bars, force and displacement measurements from performed uniaxial tensile tests on such bars, and force and displacement values from geometrically and materially non-linear simulations of the bars with imperfect geometry. The geometry data was obtained by 3D scanning the steel bars. Moreover, a script is provided that allows processing the scanned geometry data such that it can be used to generate suitable finite element meshes for geometrically and materially non-linear analyses. The force and displacement data from the uniaxial tensile tests were collected through measurements with a load cell for the force and with the help of digital image correlation measurements for the displacements. The non-linear simulations of the experiments were conducted with the computer aided engineering software Abaqus on processed approximations of the irregular scanned geometry. The described dataset can be used for better understanding the influence of the irregular geometry on the structural behaviour of wire arc additively manufactured parts. Moreover, researchers can apply the data to validate finite element simulation models and approaches for predicting the structural behaviour of different wire arc additively manufactured parts.

Background:The mechanical properties of the aorta are particularly important in clinical medicine and forensic science, serving as basic data for further exploration of aortic disease or injury mechanisms.Objective:To study the influence of various factors (age, gender, test direction, anatomical location, and pathological characteristics) on the mechanical properties and thickness of the aorta.Methods:In this study, a total of 24 aortas (age range: 54–88 years old) were collected, one hundred and seventy-four dog-bone-shaped samples were made, and then the uniaxial tensile test was run, finally, pathological grouping was performed through histological staining.Results:Atherosclerotic plaques were mainly distributed near the openings of blood vessel branches. The distribution was most severe in the abdominal aorta, followed by the aortic arch. Aortic atherosclerosis was a more severe trend in the male group. In the comparison of thickness, there were no significant differences in age (over 50 years) and test direction, the average thickness of the aorta was greater in the male group than the female group and decreased progressively from the ascending aorta to the abdominal aorta. Comparing the mechanical parameters, various parameters are mainly negatively correlated with age, especially in the circumferential ascending aorta (εp “Y = −0.01402*X + 1.762, R2 = 0.6882”, εt “Y = −0.01062*X + 1.250, R2 = 0.6772”); the parameters of males in the healthy group were larger, while the parameters of females were larger in atherosclerosis group; the aorta has anisotropy, the parameters in the circumferential direction were greater than those in the axial direction; the parameters of the ascending aorta were the largest in the circumferential direction, the ultimate stress [σp “1.69 (1.08,2.32)”] and ultimate elastic modulus [E2“8.28 (6.67,10.25)”] of the abdominal aorta were significantly larger in the axial direction; In the circumferential direction, the stress [σp “2.2 (1.31,3.98)”, σt “0.13 (0.09,0.31)”] and ultimate elastic modulus (E2 “14.10 ± 7.21”) of adaptive intimal thickening were greater than those of other groups, the strain (εp “0.82 ± 0.17”, εt “0.53 ± 0.14”) of pathological intimal thickening was the largest in the pathological group.Conclusion:The present study systematically analyzed the influence of age, sex, test direction, anatomical site, and pathological characteristics on the biomechanical properties of the aorta, described the distribution of aortic atherosclerosis, and illustrated the characteristics of aortic thickness changes. At the same time, new insights into the grouping of pathological features were presented.

Vascular diseases, such as abdominal aortic aneurysms, are associated with tissue degeneration of the aortic wall, resulting in variations in mechanical properties, such as tissue ultimate stress and a high slope. Variations in the mechanical properties of tissues may be associated with an increase in the number of collagen cross-links. Understanding the effect of collagen cross-linking on tissue mechanical properties can significantly aid in predicting diseased aortic tissue rupture and improve the clarity of decisions regarding surgical procedures. Therefore, this study focused on increasing the density of the aortic tissue through cross-linking and investigating the mechanical properties of the thoracic aortic tissue in relation to density. Uniaxial tensile tests were conducted on the porcine thoracic aorta in four test regions (anterior, posterior, distal, and proximal), two loading directions (circumferential and longitudinal), and density increase rates (0%–12%). As a result, the PPC (Posterior/Proximal/Circumferential) group experienced a higher ultimate stress than the PDC (Posterior/Distal/Circumferential) group. However, this relationship reversed when the specimen density exceeded 3%. In addition, the ultimate stress of the ADC (Anterior/Distal/Circumferential) and PPC group was greater than that of the APC (Anterior/Proximal/Circumferential) group, while these findings were reversed when the specimen density exceeded 6% and 9%, respectively. Finally, the high slope of the PDL (Posterior/Distal/Longitudinal) group was lower than that of the ADL (Anterior/Distal/Longitudinal) group, but the high slope of the PDL group appeared larger due to the stabilization treatment. This highlights the potential impact of density variations on the mechanical properties of specific specimen groups.

The human dura mater is known to impact vastly traumatic brain injury mechanopathology. In spite of this involvement, dura mater is typically neglected in computational and physical human head models. The lack of location-dependent microstructural and related mechanical data of dura mater may be considered a rationale behind this simplification. The anisotropic nature of dura mater under various loading conditions so far remains unelucidated. Furthermore, principal collagen fiber orientation is yet to be quantified for a morpho-mechanically-informed material model on the dura mater. This study aims to assess how location-dependent mechanical anisotropy is linked to principal collagen fiber orientation. Uniaxial extension tests were performed in a heated tissue bath for 60 samples from six individuals and correlated to the three-dimensional collagen structure in four individuals using second-harmonic generation (SHG) imaging. Failure stress and stretch at failure, elastic modulus, and a microstructurally motivated material model were integrated to examine local differences in dura mater morpho-mechanics. The quantitative observation of collagen fiber orientation and dispersion confirmed that collagen is highly aligned in the human dura mater and that both fiber orientation and dispersion differ depending on the location investigated. This observation provides a possible explanation for the previously observed isotropic mechanical behavior, as the main collagen fiber direction is not oriented along the anterior-posterior or medial-lateral direction at most of the mapped locations. Additionally, these site-dependent structural properties have implications for the mechanical load response and therefore potentially for the regional functions dura mater has to fulfill. The here chosen non-symmetrical fiber dispersion material model fits the data well and provides a comprehensive parameter base for further studies and future finite element models. The human dura mater greatly affects traumatic brain injury mechanisms, but it is often ignored in computational and physical head models. This is because there is a lack of detailed microstructural and mechanical data specific to the dura mater. Its anisotropic nature and collagen fiber orientation have not been fully understood, hindering the development of an accurate material model. Hence, this study combines morphological data on collagen fiber orientation and dispersion at multiple locations of human cranial dura mater, and links microstructure to location-specific load-displacement behavior. It provides microstructurally informed mechanical information towards realistic head models for predicting location-dependent tissue behavior and failure for assessing brain injury and graft material development. [Display omitted] [ABSTRACT FROM AUTHOR]

As the strength grade increases, the cold formability of high-strength steels (HSS) inevitably decreases and the brittleness tendency is obvious. However, in most existing studies on HSS forming the assumption of ductile material was commonly used, and the brittle properties of HSS were not clearly understood. In this paper, a deliberately designed uniaxial twice tensile test was employed to examine the quasi-brittle deformation and fracture behaviors of NM450TP wear-resistant steel plates. FEM models considering non-uniform mechanical properties were constructed, and DC04 plates characterized by typical ductile material were tested for comparison. The results showed that the brittle trend of NM450TP plates causes obvious localized strain during stretching, and the fracture is sensitive to the random initial imperfections. The deformation outside the necking zone is small and the deformation capacity is preserved; thus, it would be conservative to evaluate the formability of HSS by the conventional concept of percentage elongation. The non-uniform FEM models can reproduce the fracture mode of NM450TP plates during tensile tests. In comparison, the ductile DC04 specimens can "average" the mechanical properties before fracture within a wide range via large plastic deformation, and then the deformation is more uniform. The correction index n for conversion of elongation value of NM450TP plates in the Oliver formula was obtained. In the studied cases, n ranges from 0.685 to 0.752 for specimens with gauge length of 150 mm, while it ranges from 0.839 to 0.931 when the gauge length is 15 mm. [ABSTRACT FROM AUTHOR]

Iron‐based shape memory alloys (Fe‐SMAs) exhibit the particular characteristic of remembering their initial shape after a phase transformation from austenitic to martensitic. This property, along with the high strength and ductility, recommends such materials for strengthening existing structures and designing highly efficient pre‐stressed structural elements. To achieve this, pre‐strained strips or rods made of Fe‐SMA are anchored to a parent structure in the first step. Afterwards, the activation of the Fe‐SMA is triggered through heating, and the material strives to return to its initial shape. Due to the anchoring, a tensile stress is generated in the Fe‐SMA upon cooling back to room temperature, while in the parent structure, a compressive stress field is obtained. The material behaviour of the Fe‐SMA under uniaxial loading is characterized by a rounded stress‐strain relationship without a pronounced yield point, similar to cold‐formed steels. Moreover, in many currently existing applications, the material is used both in the martensitic phase (pre‐strained form before activation) and in the austenitic phase (after activation). This contribution addressed the suitability of the two‐stage Ramberg‐Osgood model for predicting the uniaxial stress‐strain response of the Fe‐SMA. The key parameters were derived based on uniaxial tensile tests and the suitability of the proposed stressstrain curves for use in advanced finite element simulations was emphasized by simulating these tests. [ABSTRACT FROM AUTHOR]

This research aims to determine the influence of the cyclic process of freezing and defrosting on the mechanical properties of the chosen glass fibres and PTFE-coated woven fabrics. The specimens were subjected to freezing at about -20˚C for 4 h and thawing by full immersion into the water at about +20˚C for 4 h. The fabric samples after 25 and 50 frozen cycles were air-dried at room temperature for one week and then subjected to uniaxial tensile tests. The same tests have been performed on a reference group of specimens, which were not exposed to temperature change. The authors determined the tensile strength, and longitudinal stiffnesses resulting from performed tests. Although the investigated coated woven fabrics expressed a reduction in the tensile strength in water soaking conditions, the performed frozen cycles don’t show a significant decrease in strength under uniaxial tensile tests.

A new Mg-4Zn X Ti-6Al-4V (TC4, of 0, 1, and 3 wt.%) alloy was successfully fabricated by a simple and low-cost gravity casting method and heat treatment at 150 °C for 24 h. The composite was examined by XRD, uniaxial tests, FESEM/EDS, potentiostat/EIS, and immersion tests for the material’s microstructures, mechanical properties, electrochemical characteristics, and corrosion resistance. Experimental results indicate that heat treatment enables the precipitation of Zn along the Mg grain boundaries and drives the co-precipitation of Al around the TC4 particles and nearby grain boundaries. Uniaxial tensile tests reveal that TC4 reinforces the Mg-Zn matrix material with higher elastic modulus, ultimate tensile stress, and toughness. The heat treatment further enhanced these mechanical properties. Electrochemical tests show that 1 wt.% TC4 composite exhibits the highest open circuit potential among all tested samples, which implies the 1 wt.% TC4-added Mg-Zn is better resistant to the oxidation of the essential metals Mg, Zn, and Al. The immersion tests in the HBSS solution further show that the 1 wt.% TC4 composite has the lowest rise of pH values after 14 days, and EDS for the corroded surface signifies that Mg is the main element vulnerable to oxidation by corrosion.

Shape memory alloys (SMAs) demonstrate a shape memory effect and superelasticity that can provide recovery performance to structural members. In this study, a round SMA bar was designed to replace the conventional deformed steel bar, particularly within the plastic hinge section of structural members. To integrate the SMA bar and the existing steel bar, a mechanical coupler was proposed by utilizing the advantages of both one-touch and threaded couplers. Uniaxial tensile tests were conducted to analyze the performance of the proposed coupler and the mechanical properties of the SMA–steel connected bar. Stress and strain relationships were examined for steel bars mechanically connected with the SMA bar and for SMA bars before and after exhibiting the shape memory effect. To induce the shape memory effect, SMA should be heated above the finished austenite temperature. Due to the difficulty of accurately measuring strain on the heated bar using traditional contact methods, we employed digital image correlation technology for precise strain measurement of the heated SMA bar. The experimental results indicate the effective application of SMA bars within the plastic hinge region of structural members using the proposed mechanical coupler.

In this paper, the characterization of 3D-printed materials that are considered in the design of multirotor unmanned aerial vehicles (UAVs) for specialized purposes was carried out. The multirotor UAV system is briefly described, primarily from the aspect of system dynamics, considering that the airframe parts connect the UAV components, including the propulsion configuration, into a functional assembly. Three additive manufacturing (AM) technologies were discussed, and a brief overview was provided of selective laser sintering (SLS), fused deposition modeling (FDM), and continuous fiber fabrication (CFF). Using hardware and related software, 12 series of specimens were produced, which were experimentally tested utilizing a quasi-static uniaxial tensile test. The results of the experimental tests are provided graphically with stress–strain diagrams. In this work, the focus is on CFF technology and the testing of materials that will be used in the production of mechanically loaded airframe parts of multirotor UAVs. The experimentally obtained values of the maximum stresses were compared for different technologies. For the considered specimens manufactured using FDM and SLS technology, the values are up to 40 MPa, while for the considered CFF materials and range of investigated specimens, it is shown that it can be at least four times higher. By increasing the proportion of fibers, these differences increase. To be able to provide a wider comparison of CFF technology and investigated materials with aluminum alloys, the following three-point flexural and Charpy impact tests were selected that fit within this framework for experimental characterization. [ABSTRACT FROM AUTHOR]

The main objective of this study was to investigate the physical and mechanical characterization of two 2 × 2 hybrid twill fabrics with the same number of yarns/cm in the warp and weft directions. One of the fabrics was composed of carbon/T300 fibers and E-glass fibers, defined as CGHF, and the other of carbon/T300 fibers and Para-aramid/Twaron fibers, defined as CAHF. Physical characterization was performed by calculating the roving linear density of each fabric. Mechanical characterization was carried out based on uniaxial tensile tests of the strands and the fabrics themselves, with the load applied in both directions: warp and weft. Another aim of this research was to investigate the macroscopic characterization of the damage mechanism according to the mechanical tests. In the uniaxial tensile test of the strands, a different result was obtained for the CGHF and CAHF carbon fiber strands, showing that in the weaving process, the fiber selected for the weft influences the mechanical response of strands and fabrics, with the test conducted in the direction of the carbon fibers. With respect to damage characterization, the integrity of the carbon fibers was practically unchanged, while the glass fibers were fragmented, and the para-aramid fibers underwent fraying. [ABSTRACT FROM AUTHOR]

As regard to cementitious composite materials added a certain dosage of fiber, estimation of tensile constitutive law through inverse analysis methods is no longer extraordinary. However, development or improvement to achieve an effective method for estimating such a tensile behavior of fiber reinforced concrete (FRC) or Ultra high-performance concrete (UHPC) is still an interesting topic to researchers. In this respect, the paper presents a development of inverse analysis method developed by Lopez to obtain the stress-strain behavior of UHPC from the four-point bending test. By applying optimization algorithm into the iterative procedure of method, an improvement could be obtained for the inverse analysis with a high degree of automation in calculation. A post-process treatment for inverse analysis results is also proposed to bring a finer agreement between the tensile behavior curve obtained by the inverse analysis and result curve of uniaxial tensile test (UTT). The effectivity of process is shown through a comparison between the result obtained by the proposed method and the result in Lopez’s public paper.

As the major connection of precast concrete structure, a novel Grouted Welded Rib Sleeve (GWRS) was proposed in this research. Six splice specimens were designed and tested under uniaxial tensile load to investigate the influence of anchorage length and inner cavity structures on their connection performance. To further investigate the failure mechanism of the specimens, a refined finite element (FE) modeling method was proposed, and the corresponding refined models were established, validated, and analyzed. This research shows that the rebar anchorage length is the key factor that controls the failure modes of the specimens. The failure loads of the specimens are mainly influenced by the failure modes. Distributing sleeve ribs close to the sleeve end with lower 25 mm spacing could enhance the confining effect of the sleeve and improve the interlocking effect between the bar and grout. The conical cracks in the grout are distributed at an angle between 35° and 45°, which is also the distributed angle of the compressive struts of the grout. The bond deterioration observed in the tests is caused by the cracking of the grout and the shearing‐off of the grout keys, resulting in the transfer of sleeve effective confining zone. [ABSTRACT FROM AUTHOR]

Purpose: Abnormal iris mechanical properties have been considered to be an important cause of pupillary-block and angle-closure glaucoma. In this research, viscoelasticity, anisotropy and location-dependence of mechanical properties of rabbit iris were investigated using uniaxial tensile test. Methods: Iris strips were taken along three directions: inner-circumferential direction (ICD), outer-circumferential direction (OCD) and radial direction (RD), respectively. Quasi-static tensile tests and stress-relaxation tests were applied on the iris strips. Then, the stress-stretch data was fitted with third order Ogden model; the stress-relaxation data was fitted with the third order Prony series model. Through comparing the tangent modulus and relaxation limit of the strips from different directions and locations, the viscoelasticity, anisotropy and location-dependence of mechanical properties of rabbit iris were explored. Results: The tangent moduli of iris at the stretch of 1.05 along ICD, OCD, and RD were 3.2 ± 1.4 kPa, 4.2 ± 2.6 kPa, 1.5 ± 0.8 kPa, respectively. Iris strips in ICD and OCD were found to have almost the same stress-relaxation behavior, and both relaxed slower than iris strips in RD. Conclusions: The mechanical properties of the iris were typically nonlinear, viscoelastic, anisotropic and location-dependent. The stress growth rate of the circumferential direction iris strip is significantly lower than that of RD and the stress-relaxation rate is significantly higher than that of the RD. That is, the iris is more prone to deformation in RD and the stress-retention ability after deformation in RD is weak, which is consistent with the fact that the iris bombe more likely happens in RD in vivo. The results of this study may also help us to establish a more accurate finite element model to simulate the flow field of humor aqueous and find the key factor of pupillary-block. [ABSTRACT FROM AUTHOR]

Porcine small intestinal submucosa extracellular matrix (SIS-ECM) used for cardiac valve repair has shown conflicting clinical outcomes with respect to calcification and failure. This may be related to differences in biomechanical properties of the material compared with the host site. The aim of this study was to compare the biomechanical properties of porcine mitral valve leaflets with SIS-ECM. Fresh porcine anterior and posterior mitral leaflet samples were cut radially and circumferentially. Similarly, 2- and 4-layered SIS-ECM were cut in orthogonal directions: length and width. Samples were subjected to a uniaxial tensile test or a dynamic mechanical analysis. Results show that the load of the porcine anterior circumferential leaflet was 39.5 N (2.4–48.5 N), which was significantly higher compared with the 2-layered length SIS-ECM which was 7.5 N (7–7.9 N), and the 4- layered length SIS-ECM which was 7.5 N (7.1–8.1 N) (p < 0.001). The load of the posterior circumferential leaflet was 9.7 N (8.3–10.7 N), which is still significantly higher when compared with the two versions of SIS-ECM. The degree of anisotropy (i.e. the ratio between circumferential-radial and width-length properties) was higher for the anterior- (ratio: 19) and posterior leaflet (ratio: 6) than the 2-layered (ratio: 5.1) and 4-layered SIS-ECM (ratio: 1.9). Especially 2-layered SIS-ECM more closely resembles the posterior mitral leaflet than the anterior mitral leaflet tissue and would be more suitable as a repair material in this position. Additionally, the anisotropic properties of mitral leaflets and SIS-ECM underscore the importance of correct orientation of the implant to ensure optimal reconstruction. [ABSTRACT FROM AUTHOR]

Recently, innovations in textile-reinforced concrete (TRC), such as the use of basalt textile fabrics, the use of high-performance concrete (HPC) matrices, and the admixture of short fibers in a cementitious matrix, have led to a new material called fiber/textile-reinforced concrete (F/TRC), which represents a promising solution for TRC. Although these materials are used in retrofit applications, experimental investigations about the performance of basalt and carbon TRC and F/TRC with HPC matrices number, to the best of the authors' knowledge, only a few. Therefore, an experimental investigation was conducted on 24 specimens tested under the uniaxial tensile, in which the main variables studied were the use of HPC matrices, different materials of textile fabric (basalt and carbon), the presence or absence of short steel fibers, and the overlap length of the textile fabric. From the test results, it can be seen that the mode of failure of the specimens is mainly governed by the type of textile fabric. Carbon-retrofitted specimens showed higher post-elastic displacement compared with those retrofitted with basalt textile fabrics. Short steel fibers mainly affected the load level of first cracking and ultimate tensile strength. [ABSTRACT FROM AUTHOR]

Human Fascia Lata (FL) is a connective tissue with a multilayered organization also known as aponeurotic fascia. FL biomechanics is influenced by its composite structure formed by fibrous layers (usually two) separated by loose connective tissue. In each layer, most of the collagen fibers run parallel in a distinct direction (with an interlayer angle that usually ranges from 75–80°), mirroring the fascia's ability to adapt and withstand specific tensile loads. Although FL is a key structure in several musculoskeletal dysfunctions and in tissue engineering, literature still lacks the evidence that proves tissue anisotropy according to predominant collagen fiber directions. For this purpose, this work aims to analyze the biomechanical properties of ex-vivo FL (collected from fresh-frozen human donors) by performing uniaxial tensile tests in order to highlight any differences with respect to loading directions. The experimental outcomes showed a strong anisotropic behavior in accordance with principal collagen fibers directions, which characterize the composite structure. These findings have been implemented to propose a first constitutive model able to mimic the intra- and interlayer interactions. Both approaches could potentially support surgeons in daily practices (such as graft preparation and placement), engineers during in silico simulation, and physiotherapists during musculoskeletal rehabilitation, to customize a medical intervention based on each specific patient and clinical condition. [ABSTRACT FROM AUTHOR]

The mechanical properties and material constitution of the aorta are important in forensic science and clinical medicine. Existing studies on the material constitution of the aorta do not satisfy the practical requirements of forensic and clinical medicine, as the reported failure stress and failure strain values for human aortic materials have a high dispersion. In this study, descending thoracic aortas were obtained from 50 cadavers (dead within 24 h) free of thoracic aortic disease, aged from 27 to 86 years old, which were divided into six age groups. The descending thoracic aorta was divided into proximal and distal segments. A customized 4-mm cutter was used to punch a circumferential and an axial dog-bone-shaped specimen from each segment; the aortic ostia and calcification were avoided. Instron 8,874 and digital image correlation were used to perform a uniaxial tensile test on each sample. Four samples from each descending thoracic aorta produced ideal stress-strain curves. All parameter-fitting regressions from the selected mathematical model converged, and the best-fit parameters of each sample were obtained. The elastic modulus of collagen fiber, failure stress, and the strain showed a decreasing trend with age, while the elastic modulus of elastic fiber showed an increasing trend with age. The elastic modulus of collagen fiber, failure stress, and strain of circumferential tensile were all greater than those for axial tensile. There was no statistical difference in model parameters and physiological moduli between the proximal and distal segments. The failure stress and strain in the proximal circumferential, distal circumferential, and distal axial tensile were all greater for the male group than for the female group. Finally, the Fung-type hyperelastic constitutive equations were fitted for the different segments in different age groups.

The performance of grouting material determines the connection reliability of prefabricated components and the overall safety of the structure. In order to realize the rapid connection of prefabricated components, improve the construction efficiency and improve the quality of component connection. The research group has developed a grouting material with fast early strength improvement and high late strength. The formation mechanism was analyzed by scanning electron microscopy (abbreviation-SEM). The reliability of grouting material was verified by uniaxial tensile test of sleeve grouting connector. The results show that : Ca(OH) _2 (abbreviation-CH), ettringite (abbreviation-Aft) and calcium silicate hydrate (abbreviation-C-S-H) are formed inside the grouting material, and the cementing system is dense inside. The skeleton formed by AFt inhibits the shrinkage of the system, which can provide support for the later compressive and flexural strength. Uniaxial tensile test results and theoretical analysis. The external reinforcement of the sleeve is broken, and the bonding performance between the grouting material and the reinforcement inside the sleeve is reliable. The internal bond stress is far less than the failure stress of the connector, which is about 50% of the failure stress.

We propose a method for obtaining reliable wide strain range equivalent stress–strain curves from tensile testing by applying 3D digital image correlation. Herein, both the front and side surfaces of the specimen were identified by the 45° tilting of the specimens. The deformation of the specimen was the most severe in the neck section, and the equivalent strain representing the entire specimen could be extracted from the neck regions on the side and front surfaces. In addition, the equivalent stress was obtained by calculating the reduction in the varying cross-sectional area from the strain information of the two surfaces. The resulting wide strain range equivalent stress–strain curves can describe nonlinear hardening behaviors up to higher strains than the conventional gauge length method. The proposed method can provide wide strain range equivalent stress–strain curves only through experiments without requiring separate finite element method simulations or correction factors.

Background: To investigate the correlation between corneal biomechanical characteristics (in vitro and in vivo) and corneal densitometry in myopia.Methods: The Pentacam (Oculus, Wetzlar, Germany) corneal densitometry (CD) and Corvis ST (Oculus, Wetzlar, Germany) exams were conducted prior to surgery for myopic patients who were intended to undergo small-incision lenticule extraction (SMILE). CD values (grayscale units, GSUs), and in vivo biomechanical parameters were obtained. The stromal lenticule was subjected to a uniaxial tensile test to obtain the elastic modulus E in vitro. We exam the correlations among in vivo, in vitro biomechanical characteristics and CD values.Results: In this study, 37 myopic patients (63 eyes) were included. The mean age of participants was 25.14 ± 6.74 years (range:16–39 years). The mean CD values of the total cornea, anterior layer, intermediate layer, posterior layer, 0–2 mm region and 2–6 mm region were 15.03 ± 1.23 GSU, 20.35 ± 1.98 GSU, 11.76 ± 1.01 GSU, 10.95 ± 0.83 GSU, 15.57 ± 1.12 GSU and 11.94 ± 1.77 GSU, respectively. Elastic modulus E (in vitro biomechanical indicator) was negatively correlated with intermediate layer CD (r = −0.35, p = 0.01) and 2–6 mm region CD (r = −0.39, p = 0.00). A negative correlation was also found between 0-2 mm central region CD and in vivo biomechanical indicator SP-HC (r = −0.29, p = 0.02).Conclusion: In myopic patients, densitometry is negatively correlated with biomechanical properties both in vivo and in vitro. With an increase in CD, the cornea deformed more easily.

This research aims to determine the influence of the cyclic process of freezing and defrosting on the mechanical properties of the chosen glass fibres and PTFE-coated woven fabrics. The specimens were subjected to freezing at about -20°C for 4 h and thawing by full immersion into the water at about ,20°C for 4 h. The fabric samples after 25 and 50 frozen cycles were air-dried at room temperature for one week and then subjected to uniaxial tensile tests. The same tests have been performed on a reference group of specimens, which were not exposed to temperature change. The authors determined the tensile strength, and longitudinal stiffnesses resulting from performed tests. Although the investigated coated woven fabrics expressed a reduction in the tensile strength in water soaking conditions, the performed frozen cycles don't show a significant decrease in strength under uniaxial tensile tests. [ABSTRACT FROM AUTHOR]

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Abstract The debris from structures produced during the blasting demolition of engineered buildings (structures) may fall near buried pipelines, which threaten the integrity of the buried gas pipeline. In this paper, the dynamic response of nearby shallow‐buried high‐density polyethylene (HDPE) gas pipelines under collapse impact loads was investigated. The stress‐strain curve and material parameters of the HDPE pipe were obtained through uniaxial tensile tests. The strain distribution of buried pipelines under collapse loading was obtained. Subsequently, a 3D nonlinear finite element (FE) model of a buried HDPE pipeline impacted by a collapsed body was established. Finally, the effects of the impact velocity, touchdown angle, touchdown mode, offset distance, and pavement structure on the mechanical behavior of buried HDPE pipelines were analyzed in detail. The results show that, as the touchdown velocity and angle of the collapsed body increase, the von Mises stress of the pipeline is significantly affected. The pipe section close to the center of the impact zone tends to be damaged due to the von Mises stress reaching the maximum tensile strength. The maximum von Mises stress of the pipeline that is impacted by the edge of the collapsed body is the smallest, but the buried pipeline undergoes the largest displacement. The rigidity of the overlying pavement structure has a significant impact on the reliability of the buried HDPE gas pipeline. The stress concentration areas of buried pipelines mainly appear on the top, bottom, and the arches of the pipeline.

The effectiveness of the use of fibers in Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) can be limited by their random orientation in the cementitious matrix. Oriented steel fibers, on the other hand, show significant promise in enhancing the tensile and flexural properties of UHPFRC specimens when the principal tensile stresses predominantly align in a single direction. Despite various proposed methods for orienting steel fibers in UHPFRC, their comparative impact on mechanical properties remained unclear. To bridge this gap, three different strategies were examined in this study, namely: i) chute with vibration table, ii) L-shaped device, and iii) electromagnetic field with vibration table, aiming at controlling the steel fibers orientation in UHPFRC specimens. Uniaxial tensile, four-point flexural, and compressive tests were conducted to examine the influence of different orientation methods on mechanical properties. The experimental findings revealed that compared to randomly oriented fibers, oriented steel fiber UHPFRC had superior tensile, flexural, and compressive strength. Additionally, fiber orientation led to improved consistency of the UHPFRC properties as well as thinner, more densely distributed cracks, regular fracture surfaces, and lower elastic modulus and Poisson's ratio. Electromagnetic field orientation proved to be the most effective orientation method, L-shaped device method the least effective due to heightened fluidity demands in the mixture, and the chute with vibration method ranked in between. This research represents a thorough investigation into the comparative efficacy of different methods for orienting steel fibers in UHPFRC, shedding new light on the optimal approach to enhance mechanical properties. • Oriented steel fibers significantly enhance UHPFRC's tensile and flexural properties. • Electromagnetic field orientation is the most effective method for steel fiber orientation. • Fiber orientation leads to more consistent UHPFRC properties and better crack distribution. • The chute with vibration table method ranks second in effectiveness. • L-shaped device method is the least effective due to higher fluidity demands. [ABSTRACT FROM AUTHOR]

This study investigated the effects of deformation-induced martensitic transformation (DIMT) on the stretchability and fracture behavior of thin sheets made from ferrous medium-entropy alloys (MEAs). Analyses of punch load-stroke curves from Erichsen tests revealed that DIMT occurred in the 60 at% Fe MEA, 64 at% Fe MEA, and 304 stainless steel (60Fe, 64Fe, and 304SS alloys, respectively). This DIMT affects necking onset, uniform elongation, and the Erichsen index (EI) under diverse stress conditions. DIMT plays a significant role in strain hardening and mechanical instability during uniaxial tests, enhancing strain hardening through martensite formation and also initiating necking due to non-uniform deformation. Particularly in 64Fe, DIMT-induced early necking resulted in reduced uniform elongation. On the other hand, biaxial Erichsen test results demonstrated further strain hardening due to martensite-induced strain accommodation, leading to enhanced resistance to deformation during biaxial loading. The distinctive shapes of punch load-stroke curves in biaxial tests, compared to stress-strain curves from uniaxial tensile tests, are a result of the interaction between DIMT and stretching directions, as well as its alloy-dependent phase stability. In 60Fe, transformed martensite contributed to strain hardening and delayed necking initiation, while extensive martensite transformation in 64Fe enhanced strain hardening further. This understanding of the complex correlation between DIMT, strain hardening, and mechanical instability holds potential for alloy optimization and developing processing strategies, applicable to automotive manufacturing and structural engineering industries. [ABSTRACT FROM AUTHOR]