Low Strain Levels Research Articles

Boosting the Output Performance of the MoS2 Monolayer-Based Piezoelectric Nanogenerator by Artificial Dual Strain Concentration.

Piezoelectric nanogenerators (PENGs) with molybdenum disulfide (MoS2) monolayers have been intensively studied owing to their superior mechanical durability and stability. However, the limited output performance resulting from a small active area and low strain levels continues to pose a significant challenge that should be overcome. Herein, we report a novel strategy for the epoch-making output performance of a PENG with a MoS2 monolayer by adopting the additive strain concentration concept. The simulation study indicates that strain in the MoS2 monolayer can be initially augmented by the wavy structure resulting from the prestretched poly(dimethylsiloxane) (PDMS) and is further increased through flexural deformation (i.e., bending). Based on these studies, we have developed concentrated strain-applied PENGs with MoS2 monolayers. The wavy structures effectively applied strain to the MoS2 monolayer and generated a piezoelectric output voltage and current of around 580 mV and 47.5 nA, respectively. Our innovative approach to enhancing the performance of PENGs with MoS2 monolayers through the artificial dual strain concept has led to groundbreaking results, achieving the highest recorded output voltage and current for PENGs based on two-dimensional (2D) materials, which provides unique opportunities for the 2D-based energy harvesting field and structural insight into how to improve the net strain on 2D materials.

Grain-level effects on in-situ deformation-induced phase transformations in a complex-phase steel using 3DXRD and EBSD

A novel complex-phase steel alloy is conceived with a deliberately unstable austenite, γ, phase that enables the deformation-induced martensitic transformations (DIMT) to be explored at low levels of plastic strain. The DIMT was thus explored, in-situ and non-destructively, using both far-field Three-Dimensional X-ray Diffraction (3DXRD) and Electron Back-Scatter Diffraction (EBSD). Substantial α′ martensite formation was observed under 10% applied strain with EBSD, and many ɛ grain formation events were captured with 3DXRD, indicative of the indirect transformation of martensite via the reaction γ→ɛ→α′. Using ɛ grain formation as a direct measurement of γ grain stability, the influence of several microstructural properties, such as grain size, orientation and neighbourhood configuration, on γ stability have been identified. Larger γ grains were found to be less stable than smaller grains. Any γ grains oriented with {100} parallel to the loading direction preferentially transformed with lower stresses. Parent ɛ-forming γ grains possessed a neighbourhood with increased ferritic/martensitic volume fraction. This finding shows, unambiguously, that the nearby presence of α and α′ promotes ɛ formation in neighbouring grains. The minimum strain work criterion model for ɛ variant prediction was also evaluated, which worked well for most grains. However, ɛ-forming grains with a lower stress were less well predicted by the model, indicating crystal-level behaviour must be considered for accurate ɛ formation. The findings from this work are considered key for the future design of alloys where the deformation response can be controlled by tailoring microstructure and local or macroscopic crystal orientations.

Tailoring Strength and Ductility of an Fe–Mn–Al–C Low‐Density Duplex Steel by Controlling the Cooling Path after Hot Rolling

The low‐density duplex steels provide a potential for the industrial application owing to their good strength‐ductility match and reduced density. In the present work, the microstructure of an Fe–8.03Mn–6.10Al–0.4C (wt%) low‐density duplex steel was adjusted by controlling the cooling path after hot rolling, which is a conventional process during the production of steel sheets and strips. A microstructure of ferrite and austenite has been achieved by annealing the air‐cooled samples, and the microstructure of furnace‐cooled annealed samples consists of banded ferrite, austenite, and martensite. This is mainly due to the fact that the austenite is more stable by refining the grain size via embedding the needle‐like α‐ferrite. The existing of martensite and the banded microstructure in furnace‐cooled annealed samples induces the occurrence of cracks during deformation, resulting in an abrupt fracture at a relatively lower strain level. However, for air‐cooled annealed samples, a good ductility of duplex microstructure ensures that the deformation can be sustained up to a much higher strain level, and the transformation induced plasticity effect plays a positive role at the later deformation stage; this contributes to the occurrence of an extra work hardening rate recovery during deformation and thus to a good strength‐ductility match.

Small-strain, non-linear elastic Winkler models for uniaxial loading of suction caisson foundations

Soils exhibit non-linear stress–strain behaviour, even at relatively low strain levels. Existing Winkler models for suction caisson foundations cannot capture this small-strain, non-linear soil behaviour. To address this issue, this paper describes a new non-linear elastic Winkler model for the uniaxial loading of suction caissons. The soil reaction curves employed in the model are formulated as scaled versions of the soil response as observed in standard laboratory tests (e.g. triaxial or simple shear tests). The scaling relationships needed to map the observed soil-element behaviour onto the soil reaction curves employed in the Winkler model are determined from an extensive numerical study employing three-dimensional finite-element analysis. Key features of the proposed Winkler model include: computational efficiency, wide applicability (it can be used for caisson design in clay, silt or sand) and design convenience (the required soil reaction curves can be determined straightforwardly from standard laboratory test results). The proposed model is suitable for small and intermediate caisson displacements (corresponding to fatigue and serviceability limit state conditions) but it is not applicable to ultimate limit state analyses.

App-based self-trainings targeting strain recovery and their effect on concentration

During the COVID-19 pandemic, many knowledge workers reported concentration problems. This can be seen as critical as concentration is an important indicator for both cognitive wellbeing and occupational success. Drawing on the load theory of selective attention, we argue that concentration problems can be caused by the strain workers experienced during the pandemic. Consequently, by associating impaired concentration with strain, we hypothesize that strengthening strain recovery is a method that potentially supports concentration in stressful times. We developed the smartphone app "swoliba" containing self-training exercises targeting recovery experiences and tested the benefit of this app with two intervention groups and one waitlist-control group. Participants of the intervention groups were asked to carry out the exercises accompanied by surveys throughout a period of 4 weeks in 2020/2021. Results show that participants in the intervention groups reported higher concentration levels and lower strain levels than those in the control group, and this beneficial effect on concentration is partially mediated via lower strain levels. We conclude that self-training apps can be an effective tool for recovery interventions reducing strain but also supporting concentration. Using two different intervention conditions, we can reliably demonstrate the beneficial effect of our swoliba training program.

Dual effect of temperature and strain on the electrical response of highly sensitive silicone elastomers doped with graphene nanoplatelets

The electrical response of graphene nanoplatelet (GNP) doped silicone elastomers (PDMS and Ecoflex) are studied under the influence of temperature, strain and both at the same time. First, temperature tests indicate a positive temperature coefficient behavior of nanocomposites over a range of −20 to 80 °C, due to higher phonon/charge scattering effects and the separation of GNP because of thermal expansion. Ecoflex sensors show higher temperature sensitivity due to their higher coefficient of thermal expansion. Second, strain tests at 20 °C reveal that nanocomposites based on PDMS promote a higher strain sensitivity due to better GNP distribution. Moreover, the optimized nanocomposites exhibit exceptional gauge factor at low strain levels (110 at 1 % and 20·104 at 7.5 %). Finally, the sensitivity of the nanocomposites to strain decreased with increasing temperature due to thermodynamic degradation of the interface between the GNP and the matrix. The prevalent contact mechanisms at higher GNP contents promote a lower reduction in temperature sensitivity when increasing the GNP content. The sensitivity of the nanocomposites to temperature and strain also decreased with the number of tensile cycling loads, particularly at higher temperatures. These findings are used to select the suitable nanocomposite for temperature, strain or dual temperature-strain sensor applications.

Synthesis of High Sn Content Ge1-x-ySixSny (0.1 < y < 0.22) Semiconductors on Si for MWIR Direct Band Gap Applications.

A systematic effort has been described to grow ternary Ge1-x-ySixSny semiconductors on silicon with high Sn concentrations spanning the 9.5-21.2% range. The ultimate goal is not only to produce direct band gap materials well into the infrared region of the spectrum but also to approach a critical concentration (yc) for which further additions of Si would decrease─rather than increase─the band gap. This counterintuitive behavior is expected as a result of the giant bowing parameter in the compositional dependence of the band gap associated with the presence of Si-Sn pairs. The growth approach in this study was based on a chemical vacuum deposition method that uses Si4H10, Ge3H8, and SnD4 or SnH4 as the sources of Si, Ge, and Sn, respectively. A fixed Si concentration near x = 0.05-0.07 was chosen to focus the exploration of the compositional space. A first family of samples was grown of Ge-buffered Si substrates. For Sn concentrations y < 0.12, it was found that the samples relaxed their mismatch strain in situ during growth, resulting in high Sn content films that had relatively low levels of strain and exhibited photoluminescence signals that demonstrated direct band gap behavior for the first time. The device potential of these materials was also demonstrated by fabricating a prototype photodiode with low dark currents. The optical studies suggest that the above-mentioned critical concentration is close to yc = 0.2. As the growth temperature was lowered in an effort to reach such values, Sn concentrations as high as y = 0.15 were obtained, but the films grew fully strained with compressive levels as high as 1.7%. To increase the Sn concentration beyond y = 0.15, a new strategy was adopted, in which the Ge buffer layer was eliminated, and the ternary alloy was grown directly on Si. The much higher lattice mismatch between the Ge1-x-ySixSny layer and the Si substrate caused strain relaxation right at the film/substrate interface, and the subsequent films grew with much lower levels of strain. This made it possible to lower the growth temperatures even further and achieve a comprehensive series of strained relaxed samples with tunable Sn concentrations as high as y = 0.21 (and beyond). The latter represent the highest Sn contents in crystalline Ge1-x-ySixSny attained to date and reach the desired yc = 0.2 range. The synthesized films exhibited significant thickness, allowing a thorough determination of composition, crystallinity, morphology, and bonding properties, indicating the formation of single-phase single-crystal alloys with random cubic structures. Further work will focus on optimizing the latter samples to explore the optical and electronic properties.

Experimental study on open core hybrid buckling restrained braces with different debonding layer geometries

AbstractThis study evaluates performances of newly developed open core hybrid buckling restrained braces (OC‐HyBRB) with debonding layers of two geometries. OC‐HyBRB has an axial load‐carrying steel core, two steel restrainers and two 3‐mm‐thick highly deformable rubber debonding layers. Debonding layer is continuous in first specimen and discontinuous in second specimen. OC‐HyBRB is designed to dissipate energy at lower strain levels through shear deformation of debonding layers. However, restrained local buckling of core first about weak axis and then about strong axis after threshold axial strain (∼2%) contributes to energy dissipation at higher strain levels. Thus, OC‐HyBRB is capable of dissipating energy in a wide range of core strain levels. Both types of OC‐HyBRBs are investigated using a specially designed test setup under a cyclic loading protocol, applied using a servo‐hydraulic actuator. Experimental force‐displacement hysteretic behaviour are found to be stable for both the specimens with enhanced stiffness at higher axial strain. This would reduce the residual deformation of the OC‐HyBRB. Thus, newly developed OC‐HyBRB would provide a simple yet efficient energy‐dissipation device for seismic response control of structures.

Laboratory performance and construction challenges for plant produced asphalt mixes containing RAP and RAS

In this study, four plant-produced asphalt mixes were considered to evaluate the performance and construction challenges of mixes containing RAP/RAS. Also, asphalt mixes were collected at two different plant-production times for each mix type to monitor the performance variability between lots. A softer base binder (PG 58–22) was used for mixes with RAS compared to the base binder (PG 64–16) used for the control mix (no RAP or RAS) and the mix with only RAP. Use of small dosages of rejuvenators and the softer binder in the RAS mixes were found to show similar performance compared to the control mix with no RAP or RAS. The results obtained from the extracted binders of these mixes indicate that mixes with RAP and RAP/RAS are expected to show higher rutting resistance and slightly lower low-temperature cracking resistance, also shown in the mix rutting and fracture cracking tests. A similar fatigue life was observed for all mixes at low strain levels in the Four-Point Beam test. However, the mix with both RAP and RAS was found to show better fatigue life at high strain levels. Similar performance test results were observed between different lots of the same mix type for most cases. Finally, there were no problems with field mixing, compaction, or finishing of the mixes containing RAP and RAP/RAS.

Optimizing heterostructure parameters for enhanced mechanical performance of Al0.1CoCrFeNi high entropy alloy

The Al0.1CoCrFeNi high entropy alloy with different heterostructure parameters, including the volume fraction of recrystallized grains (VRG) and high-angle domain misorientation (VHADM), was fabricated through cryogenic-temperature rolling and partial recrystallizing annealing. With the increase of VRG and VHADM, the yield strength and ultimate tensile strength initially increase and then decrease, while the uniform elongation consistently increases. The results indicate that the Al0.1CoCrFeNi HEA with the optimized heterostructure parameter, characterized by VRG of ∼35.9% and VHADM of ∼48.2%, shows a significant heterogeneous deformation-induced (HDI) strengthening effect. Electron backscatter diffraction results elucidate the discovery of a rapid accumulation of geometrically necessary dislocations in the domain boundary region, resulting in high HDI stress. It is observed that HDI hardening predominates at lower strain levels, while conventional dislocation hardening is more effective at higher strain levels. Higher VRG and VHADM are found to have a more significant impact on the HDI hardening effect. Our research provides valuable insights into tuning heterostructure parameters to fabricate high-performance heterostructured materials.

On the Temperature-Dependence of Deformation-Induced Martensite Formation in AISI 304L Type Steel

In this study, the deformation-induced α-martensite formation in AISI 304L steel was investigated in the temperature range between 75 °C and − 196 °C in the light of the temperature-dependence of hydrogen embrittlement phenomena. For this purpose, tensile tests with in-situ and ex-situ magnetic measurement of the α-martensite volume content as a function of plastic strain were carried out. In addition, a theoretical assessment of the temperature-dependence of the austenite stability was undertaken, evaluating chemical and non-chemical driving force contributions to the martensitic γ → α transformation as proposed by Ghosh and Olson. The experimental results clearly show an increase in the α-martensite volume content and a shifting of the phase transformation to lower strain levels upon reducing the temperature to − 75 °C. A further reduction of the temperature to − 196 °C revealed to have no significant impact on the α-martensite formation. The theoretical assessments indicate a similar temperature-dependence of the austenite stability as observed experimentally and suggest contributions of the thermal friction work at the fcc/bcc interface to be responsible for a constant austenite stability in low-temperature regimes. Additional investigations of deformed microstructures showed that element segregation effects on the local austenite stability are pronounced around room temperature, but become less relevant at low temperatures.

Origin mechanism of heterostructure nanograins with gradient grain size suppressing strain localization

Strain localization is a common deformation induced instability in many nanograined metals. Gradient nanograined metals are known to suppress the strain localization by inner coarse grains (CGs) coordinating plastic deformation. However, in this study, we found that using micropillar compression, heterostructure nanograins (NGs) with gradient grain size could suppress the strain localization and thus provide extra strain hardening without the CGs coordinating the plastic deformation. The gradient distribution of the grain size in Ti–6Al–4V alloy with heterostructure NGs plays a significant role in suppressing the strain localization. First, the gradient grain size distribution in NGs causes shear band delocalization by activating the stress-driven grain boundary migration and dislocation slip, which largely suppresses shear band localization at the low strain level. Second, when the gradient grain size distribution disappears, gradient nanograins (GNGs) change to homogeneous ultrafine grains (UFGs) stored with a large number of dislocations at the high strain level. This can refine the UFGs to NGs by dislocation-induced dynamic recrystallization and coordinate the plastic deformation in the shear bands, thereby suppressing the shear band localization at the high strain level. Hence, heterostructure NGs with gradient grain size contribute to the extra strain hardening by suppressing the strain localization. This study not only provides new insights into how GNGs suppress the strain localization, but also offers a new strategy for designing heterostructure NGs using grain boundary engineering (gradient distribution of the grain size) to improve the ductility of nanograined metals.

Ultrasensitive flexible strain sensors based on graphene nanoplatelets doped poly(ethylene glycol) diglycidyl ether: Mask breathing monitoring for the Internet of Things

Ultrasensitive and stretchable strain sensors based on graphene nanoplatelet (GNP) doped poly(ethylene glycol) diglycidyl ether (PEGDGE) for human motion monitoring purposes with remote tracking by using Internet of Things (IoT) technologies are synthesized. The quasi–static and cycling responses under both tensile and compression conditions of nanocomposites are studied in detail. On one hand, quasi-static analysis shows very high values of the gauge factor, reaching values around 50–100 at low strain levels (1–2%) and 1000–2500 at high strain levels (10%) in tensile mode, with increasing sensitivity with decreasing GNP content. In addition, electromechanical response under 500 tensile and compression load cycles up to 1%, 2.5%, and 5% strain levels proves their high stability and as a result, their high sensitivity to detect a low degree of strain levels. Three general proofs–of–concept demonstrate that these sensors can detect several types of deformations such as pressure, bending, and twisting. Finally, human breathing is monitored with the sensor attached to a conventional mask. Different breath rhythms combining the calm and excited states of a person walking are remotely sent and monitored on the internet by using different IoT platforms.

Coupled effect of pulsed current and ultrasonic vibration on deformation behavior of Inconel 718 sheet: phenomena and modeling

Multi-energy fields provide higher dimensional precision control and desirable performance for microforming processes. The constitutive model under low strain level was established to describe the coupled effect of pulsed current and ultrasonic vibration based on the Kocks-Mecking (K-M) model. Combined with the crystallographic theory, the model introduced acoustic softening effect and electroplastic effect, and described the interaction between pulsed current and ultrasonic vibration under coupled field from the perspective of energy absorption. In the research, the uniaxial tensile test of Inconel 718 sheet with thickness of 0.3 mm was carried out. The ranges of the current density and ultrasonic energy density were 20.9–50.9 A mm−2 and 15.84–57.64 J cm−3, respectively. The results showed that: the facilitation of ultrasonic vibration on dislocation generation was limited with the increase of strain, and the energy generated by ultrasonic vibration was more reflected in the change of Helmholtz free energy; when the energy generated by the current at athermal condition tended to be saturated, the increase of heat became the key to improve the electroplasticity, and the heating model caused by Joule heating effect was established. The constitutive model of coupling electric pulse and ultrasonic treatment was established, combining the characteristics of ultrasonic vibration and pulsed current; the flow stress was described by using the parameters of ultrasonic energy density and current density; The trigonometric function was used to quantitatively describe the competitive relationship between ultrasonic vibration and pulsed current in external work. Two sets of experiments were used to demonstrate the reliability of the model.

A Numerical Evaluation of Forming Failure of an Aluminum Sheet due to Splitting Damage in Hole Expansion Process

Abstract The reduction of car body weight is the principal issue of car manufacturers for reducing fuel consumption. Aluminum alloys are attractive materials for the automotive industry because they have low density and adequate strength, but they may exhibit crack formation during manufacturing processes. Generally, crack formations emerge because of tool geometry and material anisotropy. Accordingly, determination of the forming limits of aluminum alloys is essential. The hole expansion test (HET) is a significant formability process used in the automotive industry because it gives information about the stretch-flangeability limits of the material. Edge splitting (edge fracture) is a failure type seen in HET, and it limits the stretch-flangeability of the material. Therefore, the prediction of edge splitting is an essential issue for engineers in the automotive industry. In this work, HET of AA6016-O aluminum alloy was simulated with the finite element (FE) method to assess the influence of yield functions on failure prediction in HET. To this end, Hill48, Yld91, and a homogeneous fourth-order polynomial type yield criteria (HomPol4) were selected to identify the anisotropic behavior of the sheet. Analyses were carried out in Marc commercial FE software, and the Hypela2 user subroutine was incorporated into FE code. Thickness distributions in the rolling direction (RD), diagonal direction, and transverse direction (TD) of the part and around the hole edge were also predicted, and it was observed that only the HomPol4 criterion predicted excessive thinning at two locations near the RD and TD, separately. On the other hand, Yld91 and Hill48 predicted lower strain levels when compared with HomPol4. Finally, plastic work distribution around the hole edge was considered, and the predictions were compared with the experimental damaged sample. This comparison showed that HomPol4 predicted a robust plastic work localization in RD, which is consistent with the damaged sample.

Dynamic and Postdynamic Recrystallization Behavior of GWZ Magnesium Alloy Under Double‐Hit Hot Compression

Herein, dynamic and postdynamic recrystallization behaviors of GWZ magnesium are investigated. Toward this end, the single‐hit and double‐hit hot compression tests are conducted under strain rate of 0.001 s−1 at 400 °C. The prestrains of 0.1 and 0.5 are considered to investigate the effect of interpass time (5–300 s) on the compressive strength level. At the low strain level of 0.1, the contribution of Hall–Petch effect is considerable due to the occurrence of static recrystallization. In addition, the rare earth texture component is eliminated during interpass annealing. This causes increasing the strength of the material during second pass of hot compression. In contrast, at higher imposed strain, the strength level decreases with increasing the interpass time of annealing. The high amount of strain is completely consumed and the remaining stored energy is not high enough to trigger the occurrence of static recrystallization. The occurrence of metadynamic recrystallization and subsequent growth are characterized. In addition, the texture does not change in respect of the intensity or numbers/types of components. Accordingly, the observed decreasing trend of the strength is justified relying on the occurrence grain growth.

Investigation of changing SARA and fatigue properties of asphalt bitumen under ageing and analysis of their relation based upon the BP neural network

Thermal oxidation has a significant effect on asphalt binders’ saturates, aromatics, resins, asphaltenes (SARA) fractions and fatigue properties, but its effect on the SARA of different asphalt binders and the relation between SARA and the fatigue performance is not clear. In this study, thin layer chromatography/flame ionization detection (TLC/FID) was applied to analyze the SARA of the 36 specimens of original, short-term aged, and long-term aged asphalt binders. And then the viscoelastic continuum damage (VECD) model was applied to analyze these asphalt binders’ fatigue. Finally, the relation between SARA and the binders’ fatigue was determined by back-propagation (BP) neural network. The results showed that asphalt ageing can be considered to be the conversion of the light constituents to heavy constituents but the conversion ratios differed significantly for different asphalt binders. Asphalt binders of the same grade but different origins may have completely different mechanical properties and exhibit an entirely different composition conversion during ageing. Saturates can be considered the most inert constituent in asphalt. The oil source is the critical factor that determines the SARA and its degree of change during ageing. Ageing increased all of the asphalt binders’ fatigue life under a low strain level, but decreased it under high strain. The fatigue performance of asphalt binders with the same oil origin and grade but different manufacturers, did not differ significantly, either in the original or the aged states. Further, training the BP neural network showed that asphaltenes had the most significant effect on the asphalt’s fatigue behavior, followed by the resins and saturates, while aromatics had a minimal effect. And the BP neural network can forecast asphalt binders’ fatigue performance accurately based upon the SARA.

Effect of mastic specifications on the fatigue and low-temperature performance of hot mix asphalt

ABSTRACT This study aimed to evaluate the effect of mastic specifications on the intermediate and low temperatures performance of hot mix asphalt. In this research study, four different asphalt mixtures were fabricated with two types of aggregate and bitumen at three different mastic densities (defined as F/B ratios). At intermediate temperature, Four-Point Bending (4PB) beam fatigue tests were carried out at 8 Hz frequency and the strain levels of 460, 750, and 1100 microstrain. Also, the low-temperature performance of mixtures was evaluated by using Semi-Circular Bending (SCB) tests at −6°C, −18°C and −12°C, −24°C for PG 64–16 and PG 58–22 fabricated mixtures, respectively. Fatigue test results showed that the fatigue life of asphalt mixtures was more influenced by the mastic density at the lower strain level. Moreover, a minimum mastic density was necessary for improving fatigue performance. The SCB test results revealed that increasing the mastic density makes higher values in the mixture’s fracture energy, fracture toughness, cracking resistance index (CRI), and tensile strength. Also, the low-temperature performance of asphalt mixtures containing aggregate with a high abrasion value (AAV) was more dependent on the mastic density.

A new microstructural refinement mechanism of ultra-large β grains in near-β titanium alloys during primary hot-working

In this work, the multi-step hot-working of a near-β titanium alloy, Ti-55511 alloy with centimeter-sized grains, was performed at 1170 °C. It was confirmed that the static/metadynamic recrystallization during interpass annealing was the primary mechanism responsible for the microstructural refinement. Meanwhile, a new breakdown mechanism of the ultra-large β grains with 〈001〉 preferential orientation was observed during deformation, which was essentially different from the traditional discontinuous or continuous dynamic recrystallization. That is, new grain boundaries and even boundary networks were produced interconnecting the corners/protrusions of the 〈001〉 -orientated grains through a low-angle grain boundary merging mechanism, which progressively severed the large β grains into smaller ones. Such a breakdown mechanism may be an important complement for microstructural refinement during primary hot-working, which allowed the breakdown of the ultra-large β grains under fairly low strain level.

Hypertension Reduces Aortic Strain in Both Sexes, but only Aorta from Female Rats Showed Increase in Stress: The Role of Appropriate Normalization Method to Evaluate Strain-Stress Parameters

The gold standard of arterial stiffness measurements in isolated aorta is the stress-strain (SS) relationship. Wall thickness (WT) and artery inner diameter (ID) are variables that plot the SS curve and should be normalized to the dimensions of the individual subject. Previously, we used measurements from the current literature, but the data collected were not accurate. Therefore, we hypothesized that the measurements of the vascular structure using echocardiogram (ECHO) should be applied to evaluate tissue puller to obtain SS data. With that, we also hypothesized that aorta from spontaneously hypertensive rats (SHR) has greater stress and lower strain levels than normotensive Wistar rats. To test this hypothesis, thoracic aorta parameters from 3-month-old male Wistar (WM) (body weight: 449±6.87g, n=4), SHR male (SM) (body weight: 295±3.34g, n=4), Wistar Female (WF) (body weight: 250±8.50g, n=4), and SHR Female (SF 169.4±2.69g, n=4) rats were measured from an ECHO. After, animals were killed and aortas were cut in 2 mm segments and mounted on Tissue Puller to measure SS. The inner diameter (ID) and wall thickness (WT) were measured by the ECHO for all animals: [WM (WT: 0.519±0.014mm, ID: 2.042±0.11mm), SM (WT: 0.485±0.026mm, ID: 2.023±0.055mm), WF (WT: 0.504±0.01mm, ID: 1.628±0.092mm), SF (WT: 0.521±0.011mm, ID: 1.64±0.099mm)] and there were no significant difference between these values. We then normalized the SS curves to each of the arteries’ parameters for ECHO and we found there were significant decreases in the strain values in aorta from hypertensive rats, regardless of sex (WM: 1.775±0.108 vs SM: 1.370±0.058; p=0.0146), and (WF: 2.056±0.218 vs. SF: 1.713±0.224; p=0.0517). We found a trend in the stress from female rats (WF: 1367±61 mN/mm2 vs SF 2361±391 mN/mm2; p=0.0597). There were no differences between male rats (WM:1.269±153 mN/mm2 vs SM: 1319±80 mN/mm2; p=0.671).Overall, these data show that ECHO should be used to accurately measure rat aorta structural parameters under the tissue puller. They also show SHR and Wistar were different in both sexes in strain, but only female SHR vs Wistar showed differences in stress. National Institutes of Health - R00GM118885, R01HL149762, and R00HL151889. and McNair Junior Fellows (MJF) Program This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.