Failure Strain Values Research Articles

Experimental research on shear resistance performance of fabricated reinforced concrete layered beams

The construction of prefabricated beams includes two steps: prefabrication and cast in-situ. However, for the bearing beam, the shear stress on the joint surface of these two parts may be large. This is detrimental to the shear resistances of layered beams. To evaluate the shear resistance performances of such layered beams, three different influencing factors—the ratio of the precast layer height to the beam height, shear-span to depth ratio, and the treatment method of new and old concrete interface—were considered, and shear resistance tests of 9 groups of beams were carried out. The failure mode, carrying capacity, deflection, and strain value of each test beam were analyzed. The results show that the shear bearing capacity of layered beams decreases by 34.12% with the increase of shear-span to depth ratio, and with the increase of the ratio of precast layer height to beam height, the shear bearing capacity of layered beams decreases by 14.17%. The shear bearing capacity of the layered beam with steel bars inserted in the vertical direction of the new and old concrete interface is about 8.43% higher than that of the layered beam without steel bars. According to the test results, the formula for calculating the shear bearing capacity of layered beams considering the layered height ratio and shear-span to depth ratio was proposed. At the same time, the interface resistant shear design method concerning reinforced concrete layered beams is proposed.

Effect of warp yarn paths on the symmetrical cyclic bending fatigue properties of 3D woven composites

AbstractIn this study, the symmetric cyclic bending fatigue properties of three‐dimensional (3D) woven composites under the condition of R = −1 were investigated. Three types of 3D preform structures with different warp yarn paths were designed, and a bending fatigue testing fixture suitable for 3D woven composites under R = −1 conditions was developed. In addition, the bending fatigue properties, damage mechanisms, and failure modes of three composites were studied. The results showed that the warp yarn paths were responsible for the differences in quasi‐static bending properties. The bending fatigue properties were related to the warp yarn paths and applied stress. Satin woven (SW) structure had the highest bending fatigue failure strain value, followed by the twill woven (TW) structure, and the plain woven (PW) structure had the lowest. The bending fatigue limits of PW, TW, and SW structures were 40% (136 N), 40% (210.5 N), and 16% (119.4 N) stress levels, respectively. The bending fatigue failure mode of 3D woven composites was softening failure under the condition R = −1.Highlights The warp yarn paths significantly affects the quasi‐static bending properties. A symmetrical cyclic bending fatigue testing fixture was developed. The symmetrical cyclic bending fatigue life of 3D woven composites was obtained. SW composites have the highest bending fatigue failure strain value. The symmetrical cyclic bending fatigue failure modes were softening failures.

State-of-the-Art Review on Utilization of Fly Ash in Pavement Structures

The use of fly ash in construction has been on the rise, yet its application in pavement construction remains relatively underexplored. This study addresses this gap by critically reviewing 70 years of research on fly ash usage in pavement engineering, offering valuable recommendations. Class 'C' fly ash is employed for soil stabilization, while class 'F' is used in concrete. In both flexible (asphalt) and rigid (concrete) pavements, fly ash primarily functions as a filler material. Fine ash, owing to its fineness, enhances asphalt concrete by reducing void ratios and water sensitivity, as well as easing subgrade compaction while increasing compressive strength. Incorporating fly ash into Hot Mix Asphalt (HMA) enhances resistance to cracking and oxidative ageing. Adding fly ash (up to 25%) significantly boosts soil failure stress and strain values by 106% and 50%, respectively, while a combination of 8% lime and 18% fly ash yields maximum shear strength. A modest amount of lime (1-2%) mixed with 10% fly ash achieves a maximum dry density of 1.98 gm/cm3 at an optimal water content of 12.62%. Additional testing by researchers corroborates and validates the findings of this literature review.

Freeze-Thaw resistance and mechanical properties of UHPC reinforced with a lower amount of hybrid fibers

Sustainable development is becoming critical in many industrial fields, including building materials. The rapid development of the construction industry in Kazakhstan requires construction materials having high-quality, low maintenance, and good durability. The main durability issue of construction material associated with Kazakhstan’s severe climate is the volume change of water in concrete caused by the freezing and thawing (F-T) cycles, which threatens the material’s strength and microstructure. Therefore, ultra-high-performance concrete (UHPC), a relatively new material with high compressive and tensile strength and improved microstructural properties, is suggested. Nevertheless, a limited number of researches have been done regarding the F-T resistance of UHPC. This research focuses on the effect of combining two types of fibers (steel and polypropylene (PP) fibers) on the compressive, flexural, and direct tensile strength and F-T resistance of UHPC. Test results indicated higher dosages of PP fiber in UHPC increased strength before exposure to F-T cycles. Adding PP fiber to UHPC led to more prolonged strains for each UHPC mixture. However, adding more steel fibers was beneficial for UHPC exposed to F-T cycles. Although mixtures with high steel fiber dosage presented a more brittle type of failure and lower strain values than mixtures with higher PP fiber dosage, the compressive, flexural, and tensile strength of UHPC mixtures containing higher steel fiber dosages increased after 90F-T cycles. Relative dynamic modulus of elasticity (RDME), which is a common indicator of F-T resistance of concrete, tends to increase for all tested mixtures, with the highest values belonging to ones with higher steel fiber dosage. Hence, it is suggested that UHPC with higher steel fiber dosage is more beneficial in terms of the F-T resistance of UHPC.

A study to characterize the mechanical properties and material constitution of adult descending thoracic aorta based on uniaxial tensile test and digital image correlation.

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 24h) 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.

Performance Evaluation of Clay Plastic Concrete of Cement and Epoxy Resin Composite as a Sustainable Construction Material in the Durability Process

In this research, bentonite soil was stabilized with cement and epoxy resin additives by gradually increasing the ratio of epoxy resin to water to withstand six successive wetting/drying (W/D) cycles. Unconfined compressive strength (UCS) tests were performed on the stabilized samples after curing and 24 h of soaking in the third and sixth cycles. The swelling–shrinkage potential of bentonite soil was evaluated indirectly by analyzing its stress–strain behavior. The results showed that for different amounts of cement, the minimum ratio of epoxy resin to water added to bentonite soil to last up to six cycles was equal to 1:1. Also, by stabilizing the bentonite soil so that the total weight of the optimum moisture content was replaced with epoxy resin, the strength and rigidity attained the level of normal concrete, with the difference that the ductility was much more significant. The failure strain value increased by 32 times, and the plastic region of the stress–strain curve expanded over the wide strain interval with a length of about 5%. Clay plastic concrete design consisting of cement and epoxy resin develops sustainable ground improvement methods.

A study on the influences of a hygrothermal environment on the compressive strength and failure criteria of asphalt mixtures based on true triaxial tests

Based on a high-pressure servo static and dynamic true triaxial test machine (tawz-500/300), uniaxial and true triaxial tests of AC-25C asphalt mixtures under different heat moisture coupling treatments were performed, and the triaxial compressive strength value was determined by mathematical treatment. The test results show that in the range of 20–60 °C, the uniaxial and triaxial compressive strength of the AC-25C asphalt mixture decreases with increasing drying and soaking environment temperature. In the temperature range of 20–40 °C, the drying temperature sensitivity and soaking temperature sensitivity of the asphalt mixture with compressive strength and failure strain value as indices are the maximum. The increase in the intermediate principal stress can improve the triaxial compressive strength, and the increase reaches the maximum when the environmental treatment temperature is 40 °C. The maximum stress ratio is in the range of σ2/σ3 = 0.25 to σ2/σ3 = 0.5. The failure forms of uniaxial tension and triaxial tension are mainly caused by tensile stress. The influence of temperature, humidity and stress ratio on triaxial failure strength is analysed. The relationship between the failure strength and temperature coefficient k is established using a variety of failure criteria, which can provide an experimental and theoretical basis for the mechanical analysis of asphalt mixtures under complex stress states.

An evaluation of fiber-based damage for assessing the failure of aortic tissue: comparison between healthy and aneurysmal aortas

The decision of surgical intervention for an aortic aneurysm is usually associated with an assessment of risk of its rupture. Global rupture risk assessment parameters like wall diameter and growth of the aneurysm over time often fail at predicting the risk of rupture with accuracy. This paper will investigate the hypothesis that the tissue’s microstructure determines its macroscopic failure. To this aim, two different testing protocols have been implemented. Human ascending thoracic aortic aneurysm (ATAA) tissue samples were subjected to bulge-inflation testing until rupture coupled with multi-photon microscopy (MPM) imaging. Image stacks of the sample were acquired at different pressure levels. Additionally, porcine aorta samples were tested under uniaxial tension until failure and their response was recorded. Prior to mechanical testing, MPM image stacks were acquired at four different zones on the sample. The image stacks acquired at the load free state were used to extract morphological information relating to collagen fibers. Then, an inverse random sampling approach was used to generate pseudomorphological parameters for network reconstruction. A discrete model of the collagen network signifying its stochastic nature was then developed, including both prefailure and post-failure mechanics. The model was able to replicate the mechanical response and failure of the tissue, and demonstrated that fiber-based damage can strongly shape the macroscopic failure response of the tissue. Identified values of collagen fiber failure strain were in the range of 8.8 to 29.3% in the case of aneurysmal samples, and 18.7 to 25.5% in the case of porcine samples. A statistical analysis enabled the characterization of correlation between fiber morphology and tissue failure. The model may serve as a useful tool for predicting macroscale failure of the aortic wall based on the variations in microscale morphology.

Strain localization analysis in materials containing randomly distributed voids: Competition between extension and shear failure modes

Strain localization is often a precursor to the ductile failure of materials. This paper investigates plastic strain localization phenomena in the case of random microstructures, namely cubic cells made of an elastic-perfectly plastic matrix embedding distribution of identical non-overlapping spherical voids. The consideration of random microstructures allows for a better representation of the interaction between voids and greater diversity of failure modes than single-void (or unit) cells. The cells are simulated by means of the finite element (FE) method for proportional stress loading paths with controlled stress triaxiality and Lode parameters. Strain localization is detected by Rice’s criterion computed at the cell level. This criterion is shown to accurately capture the onset of localization and the type of failure mode, either extension or shear banding. Moreover, the influence of the loading orientation, i.e. the orientation of the principal axes of the applied stress tensor with respect to the microstructure cube, is systematically studied. Significant anisotropy of failure behavior is observed, especially in the case of single void unit cells, which can be attributed to the intrinsic anisotropy of the simulation cells. Finally minimal failure strain values at localization with respect to all loading orientations are found. A zone of reduced ductility is observed under generalized shear loading conditions.

Feasibility of elastomeric composites as alternative materials for marine applications: A compendious review on their properties and opportunities

The term elastomer is a curtailment of two words, which are elastic and polymers. Accordingly, elastomers are polymer materials with elasticity. The significant challenges hindering the development of materials for naval applications, similar to other engineering sectors, include achieving a competitive light elastomeric structure. Marine structures are susceptible to various damage responses due to various loads throughout their service life. Being flexible, elastomer has a low modulus of elasticity, exhibits higher values of failure strain and yield strength. In these regards, elastomers are attractive materials for applications that require elasticity because they offer substantial advantages compared to traditional materials. However, the low fire resistance of these elastomeric materials jeopardizes their use in some critical applications. As a result, elastomeric blends and composites containing flame retardant (FR) additives are commonly used. On the other hand, elastomers possess (i) high strength-to-weight ratio, (ii) excellent impact properties, (iii) low infrared, magnetic, and radar signatures, (iv) excellent durability, and (v) high resilience to extreme loads. Hence, the scope of this study focuses on review and awareness regarding the feasibility of marine applications of elastomers/elastomeric composites, their current scientific and technological drawbacks, and future outlooks or prospects to support several applications in the marine industry.

The Effect of Ti–B and Sr on the mechanical behaviour of the Zinc–Aluminum-based ZA-12 alloy produced by gravity casting

Abstract In this study, the effect of Ti –B (0.05 – 0.7 wt.% Ti, 0.01 – 0.13 wt.% B) and Sr additions (0.05 – 0.7 wt.%) on the hardness, ultimate tensile strength (UTS), strain and fatigue properties of the gravity cast Zn – Al-based ZA-12 alloy was investigated. While the Ti –B additions had no significant effect on the hardness of the alloys, the Sr additions lowered the hardness by a small amount. UTS and fatigue resistance of the ZA-12 alloy increased with 0.05 wt.% Ti, but the addition of 0.05 wt.% Sr to the standard alloy did not change these properties significantly. In excess of 0.05 wt.% Ti and Sr, the UTS and fatigue resistance of the alloys decreased and reached a lower value than that of the standard alloy. The failure strain only increased for the ZA-12 alloy containing 0.05 wt.% Ti, then decreased with further increase in Ti content. The failure strain values of the alloys decreased with addition of Sr. Metallographic examination indicated that the addition of Ti –B strongly modified the microstructure of the standard ZA-12 alloy, but Sr did not. Ti and Sr have also formed complexshaped intermetallic compounds, which were identified as Al5Ti2Zn and Zn5Al3Sr by X-ray diffraction and EDS analyses. It can be suggested that these particles cause a decrease in UTS, fatigue resistance, and strain to failure of the ZA-12 alloy.

Effect of Grain Boundaries’ Doping on the Mechanical Properties of Nitrogen-Doped Bicrystalline Graphene

Grain boundaries and doping play an important role in influencing the mechanical behaviour of materials. In this article, Tersoff potential based molecular dynamics simulations were employed to comprehensively investigate the effect of random N doping on the mechanical behaviour of pristine and bicrystalline graphene nanosheets. For bicrystalline nanosheets, three types of grain boundaries with high, transition and low tilt angles, were considered here. Each grain boundary model was doped as a whole nanosheet, only grain boundary area, and/or non-grain boundary area. Our results show that the configurations with doping of grain boundary area showed more deterioration in failure stress and failure strain values than the configurations with doping of the non-grain boundary area. Also, N doped pristine nanosheets and the configurations with non-grain boundary area doping showed a monotonic increase in Young's modulus while a monotonic decreasing-increasing trend was predicted for the rest of the configurations. These results show that the doping of the grain boundary area is more detrimental to the mechanical properties than the doping of the non-grain boundary area. Moreover, even after N doping, the high angle grain boundaries show higher strength as compared to the low angle grain boundaries.

Comparison of numerical approaches for structural response analysis of passenger ships in collisions and groundings

The dynamic response of ships following grounding and collision accidents may be influenced by structural topology as well as operational and environmental conditions. Traditionally, the consequences of such events may be assessed by crude empirical methods or laborious experiments. Computational methods offer a useful alternative in terms of accurately capturing crushing mechanisms also accounting the influence of surrounding water. This paper presents a benchmark study that compares the structural dynamic response by explicit nonlinear FEA approaches and the semi-numerical super-element method. Simulations for typical accident scenarios involving passenger ships confirm that implementing the influence of hydrodynamic restoring forces in way of contact may be useful for either collision or grounding. Yet, for grounding scenarios, the damaged area resulting from analytical simulations appears to be sensitive to the failure strain values adopted to model the rupture of the ship bottom floors.

Theory for designing mechanically stable single- and double-walled SiGe nanopeapods

Herein, we utilized molecular dynamic (MD) simulations using LAMMPS software and selecting Tersoff and Lennard-Jones potentials to design and investigate mechanical properties of (8,8), (9,9), (10,10), and (11,11) single-walled and (8,8)@(11,11) double-walled silicon-germanium (SiGe) armchair nanopeapods. The number of encapsulated fullerenes and the working temperature were changed as variables to evaluate the mechanical properties. The larger nanopeapods had lower Young's modulus and failure strain, but, surprisingly enough, no significant variation was found in failure strain values by increasing the number of Si30Ge30 cages and the temperature (300-900K). Overall, higher mechanical properties were the case for double-walled SiGe nanopeapods and that the more the number of encapsulated cages, the lower the mechanical properties whatever the nanopeapod. Amazingly, fullerenes remained undamaged even after the SiGe nanopeapods ruptured. Thus, thermally/mechanically stable nanopeapods developed theoretically herein can be considered potential super-carriers for drug and gene encapsulation.

Evaluation of Monkman–Grant strain as a key parameter in ductility exhaustion damage model to predict creep rupture of grade 92 steel

Conventional strain-based numerical prediction assumes that failure occurs when ductility is exhausted or accumulation of creep strain reaches the critical failure strain. Due to instability at the onset of rupture, the failure strain value appears to be scattered and leads to the erroneousness in prediction. In this paper, a new local constraint-based damage model incorporating the Monkman–Grant ductility, as a measure of strain during uniform creep deformation stage, was implemented into a Finite Element (FE) model to predict the creep damage and rupture of Grade 92 steel under uniaxial and multiaxial stress states. The prediction was applied on plain and notched bar specimens with various notch acuities. The uniaxial stress-dependent Monkman–Grant (MG) failure strain was adopted in the FE to simulate the influence of the constraints which were induced by the creep damage. The implication of reduced failure strain in long-term creep time on the rupture prediction is discussed. The multiaxial MG failure strain of the notched bar, which has a lower value than uniaxial failure strain due to the geometrical constraint, was estimated based on the linear inverse relationship between normalised MG failure strain and normalised triaxiality factor. It was found that the results obtained from the proposed technique were in good agreement with the experimental data within the scatter band of ± factor of 2. It was shown that MG failure strain can be used as an alternative to strain at fracture. MG strain outweighed strain at fracture because the determination of its value only required short-term testing to be performed. In most cases considered in the present investigation, the rupture-type fracture was predicted, however, there was evidence that under high constraint and low stress, stable crack propagation occurred before fracture. The location of the maximum creep damage was found to be dependent on the creep time, geometry or acuity level of the specimen. For sharp notch specimen, the failure was initiated near the notch root, however, as the notch radius increased, the initiation location moved further away towards the specimen centre.

Electromagnetic and Mechanical Characterization of Iron Reinforced Natural Fiber Composites for Microwave Absorbing Applications

The development of the natural fibre-based efficient microwave absorbing composite that provides good tensile properties in addition to electromagnetic properties is still a challenging task. In this work, experimental studies are performed to develop iron-reinforced jute fibre-based novel hybrid microwave absorbing composites. The main objective of this experimental study is to achieve better absorption and wide absorption bandwidth with the acceptable tensile property. Therefore, four samples have been fabricated and tested with constant jute fibre content and distinct iron contents. The electromagnetic parameters (εr and μr) have been measured using the waveguide-based microwave measurement technique. An optimal sample is found to possess good microwave absorption properties at X-band. Further, the fabricated composite is subjected to the tensile test and it has been found to possess an average Young’s modulus value of 9.4 GPa, final failure strain value of 0.08, and an average ultimate tensile strength value of 49 MPa. Scanning electron microscope analysis was used for the tensile tested specimen to predict the internal failure behavior and determine the major modes of failure such as fiber breakage, matrix cracking, and delamination failure. The obtained results reflect the potential of fabricated composite for various strategic applications.

Effect of material properties on ballistic energy absorption of woven fabrics subjected to different levels of inter-yarn friction

Inter-yarn friction plays a significant role in ballistic energy absorption of woven fabrics. In the past decade, a few studies have been reported on the effect of inter-yarn friction on ballistic energy absorption. It has been reported that ballistic energy absorption of a woven fabric increases until an optimum value of the coefficient of friction11COF = Co-efficient of friction (COF) and decreases beyond that. However, a fundamental understanding of how yarn material properties affect this optimum friction value is still elusive. The effect of yarn material properties on different modes of ballistic energy absorption, when subjected to different inter-yarn friction level, is also not understood. In order to address this lacuna, this work presents a detailed numerical analysis of woven fabrics with different material properties but constant toughness subjected to different inter-yarn friction using the finite element framework. The results show that for materials with a low value of longitudinal modulus and higher value of failure strain, the threshold friction level is of lesser magnitude than in materials with a high value of longitudinal modulus and lower failure strain value. An explanation of this phenomenon has also been attempted based on a study of longitudinal stress wave velocity in woven fabrics with different levels of inter-yarn friction. It has also been found that an increase in the inter-yarn friction level increases the ballistic energy absorption in fabric strain energy mode while it decreases the energy absorption in fabric kinetic energy mode up to the threshold friction value. The results are expected to be a guide to choose woven fabrics while attempting to improve their ballistic performance by impregnating them with shear thickening fluids22STF = Shear thickening fluid (STF).

Constitutive equation determination and dynamic numerical modelling of the compression deformation of concrete

AbstractThe dynamic compression deformation of an in‐house cast concrete (average aggregate size of 2–2.5 mm) was modelled using the finite element (FE), element‐free Galerkin (EFG) and smooth particle Galerkin (SPG) methods to determine their capabilities of capturing the dynamic deformation. The numerical results were validated with those of the experimental split Hopkinson pressure bar tests. Both EFG and FE methods overestimated the failure stress and strain values, while the SPG method underestimated the peak stress. SPG showed similar load capacity profile with the experiment. At initial stages of the loading, all methods present similar behaviour. Nonetheless, as the loading continues, the SPG method predicts closer agreement of deformation profile and force histories. The increase in strength at high strain rate was due to both the rate sensitivity and lateral inertia caused by the confinement effect. The inertia effect of the material especially is effective at lower strain values and the strain rate sensitivity of the concrete becomes significant at higher strain values.

Characterization of the Fatigue Behavior of SLS Thermoplastics

The selective laser sintering (SLS) is an additive manufacturing technology with clear potential for producing high quality polymeric components of various thermoplastic polymers and elastomers which can be used in demanding engineering applications under complex service loading conditions. The prerequisite for these applications is that the stiffness and the tensile strength of the SLS specimens is in the same range as for injection molded specimens using a proper parameter set of the SLS process and qualified materials. While the tensile strength of SLS printed polymers is recently determined by many researchers, hardly any data are available about the fatigue behavior of SLS polymers on specimen level and even less on component level. Cylindrical specimens with and without round notch have been designed and additively manufactured using PA12 and TPU SLS grades in two different printing directions (vertical and horizontal). The monotonic tensile behavior was characterized over a wide loading rate range (0.1 to 100 mm/s) and the tensile strength and failure strain values were determined. The fatigue behavior was characterized under cyclic loading conditions at various stress ratios (R=0.1, -1), at a constant frequency of 5 Hz at 5 stress levels. Stress vs. cycle number-to-failure, Nf points were determined for constructing conventional S-N curves for the materials investigated. A distinct anisotropy of the tensile strength and failure strain was recognized for the SLS TPU investigated.

Biomechanical Properties of the Periaortic Abdominal Tissue: It is Not as Fragile as It Seems.

The perivascular adipose tissue has been studied as a critical element that could influence physiological and disease processes of the vessel covered by it. In terms of anatomy, during the abdominal aorta's dissection, it is possible to identify the periaortic adipose tissue and the periaortic parietal peritoneum lying over it, sealing the retroperitoneal space. They seem to be fragile layers, with apparently no biomechanical role in the abdomen. However, it is well known that most cases of ruptured abdominal aortic aneurysms (AAAs) that reach the emergency department still alive present retroperitoneal bleeding contained by the previously mentioned two-layer combination, eventually allowing time for surgical treatment. In previous studies about aortic wall stress, tension, and AAA rupture prediction, only information concerning the vessel wall itself is highlighted. Therefore, the present work aims to study the biomechanical and histological properties of the periaortic tissue, comparing them to the same variables measured in aortic wall samples described in the medical literature. Samples of periaortic tissue were harvested from 27 individuals during necropsy. Smoking status and the presence of AAAs were observed. Biomechanical uniaxial destructive tests were performed up to samples' rupture. Values of failure stress, tension, and strain were obtained. Samples were also harvested for histological analysis. Periaortic tissue presented less amount of collagen in smokers than in nonsmokers (P=0.017). The periaortic tissue seems to be more elastic than aortic walls described in the literature (strain: 0.75±0.37). Analyzing periaortic tissue failure stress (56.8±101.26N/cm2) and tension (7.65±4.99N/cm), it has at least 52% and 55%, respectively, of the stress and tension described in the medical literature for AAA walls. The periaortic tissue presents less collagen fibers in smokers than in nonsmokers. The periaortic tissue seemed very delicate during an autopsy, but the study of its biomechanical properties showed that it presents more than half of the resistance of an AAA wall. This information suggests this tissue might have a mechanical protective role against massive bleeding when it comes to an aortic rupture. Therefore this tissue's biomechanical information should be included in computational models on enlargement and rupture prediction of AAAs.