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In the present study, the evaluation of FSW input parameters on output response ultimate tensile strength (UTS) of the friction stir welded AA6101-C11000 joint is in agreement. The response surface methodology (RSM) was adapted for generating the mathematical regression equation to predict the UTS and to develop the FSW parameters to attain the highest UTS of the FSW joints. The central composite design (CCD) method from RSM with five levels and three factors, i.e., tool rotational speed, feed rate, and tool offset used to conduct and minimize the number of tests. During FSW, base sheet cu (hard metal) was stationed on the advancing side (+1 mm, +1.68 mm tool offset) and the base sheet Al (soft metal) on the retreating side (−1 mm, −1.68 mm tool offset). The radiography studies were accomplished to inspect the internal flaws of the FSW joints (Al-Cu).The XRD and SEM investigation of the ruptured specimens during the tensile test to evaluate the IMCs phase anatomy and fracture analysis. The maximum UTS value measured during the experimental work was 142.69 MPa at 1000 rpm, 40 mm min ^−1 , and −1.68 mm tool offset. The highest joint efficiency obtained was 82% compared with the AA6101 UTS value. RSM adapted for this work was 92% accurate and satisfactory.

It is a requirement of modern age industries, especially the aerospace, automobile, and shipbuilding sectors, to manufacture high strength and low weight dissimilar aluminium alloy welded joints. Therefore, the aim of this project is to investigate the effect of tool rotation speed, feed rate, and pin type on the ultimate tensile strength (UTS) of dissimilar aluminium alloys (2024 Al and 5754 Al) in friction stir welded joints. Nine experiments have been performed using an orthogonal array (L9) of the Taguchi method. An analysis of variance (ANOVA) established that pin type is the most prominent parameter, followed by tool rotation speed and feed rate. The optimal value of ultimate tensile strength (268 MPa) was achieved at 1.5 mm/s feed rate, 1600 rpm speed, and type 1 of pin. A confirmation test shows that there is a high correlation between the estimated and actual values of UTS.

This experimental investigation aims to formulate quadratic regression based empirical model taking into account the parameters of friction stir welding (FSW) process for predicting the optimized process parameters to maximize the response (i.e., ultimate tensile strength) of the distinctive alloys of Mg joints. Parameters of FSW process taken into consideration includes tool’s traverse speed, axial force and rotational speed of tool and response being the fabricated joint’s tensile strength. A central composite rotatable category 3–factor, 5 level design based matrix was formulated and response surface methodology was used to obtain regression based models, to generate contour plots and to visualize the interactive impacts of parameters on the joint’s tensile strength. Formulated quadratic regression based model was validated employing analysis of variance. Comparison amidst the realistic and anticipated values of the response announced the superior fitting accuracy of the formulated quadratic model. For a constant tool’s rotational speed (of 1000 rpm to 1250 rpm), the tensile strength was observed to be highly sensitive to the axial force values than the tool traverse speed values. Mean tensile strength of the friction stir welded AZ31B, AZ80A, AZ91C, AM50A and ZK51A-T5 Mg joints during the employment of optimized process parameters were found to be 217.5 MPa, 251.4 MPa, 231.9 MPa, 192.1 MPa and 173.2 MPa respectively, thereby exhibiting perfect agreement with the anticipated values.

This study introduces a modified differential evolution approach (MoDE) for evaluating the optimal objective and parameter values of the friction stir welding (FSW) process of dissimilar materials: AA5083 and AA6061. The aim of this study is to investigate the ultimate (UTS), maximum hardness (MH), and minimum heat input (HI) of the weld zone. The controlled welding parameters were shoulder diameter, rotation speed, welding speed, tilt angle, pin type, reinforcement particle type, and tool pin movement direction. The D-optimal experimental design method was used to create the experiment and obtain the mathematical model for optimizing the targeted objectives. The optimal rotational speed, welding speed, shoulder diameter, tilt angle, pin-type, additive type, and tool pin movement are 1162.81 rpm, 52.73 mm/min, 21.17 mm, 2.37 degrees, straight cylindrical, silicon carbide, and straight movement direction, respectively. The optimal values for UTS, MH, and HI are 264.68 MPa, 105.56 HV, and 415.26 °C, respectively. The MoDE outcome exceeded particle swarm optimization (PSO), the original differential evolution algorithm (DE), and the D-optimal design (experiment) results. The MoDE provides better UTS, MH, and HI than other approaches by an average of 8.04%, 4.44%, and 2.44%, respectively. In particular, when comparing results produced by using various approaches, we discovered that the MoDE results are 7.45%, 4.45%, and 3.50% better than PSO, DE, and the experimental results, respectively. All methods were evaluated for their reliability by comparing the results of actual experiments to those predicted by theory, and we discovered that the MoDE yielded the smallest percentage difference between the two, at 1.49%, while PSO and DE yielded differences of 5.19% and 3.71%, respectively.

The relations between ultimate tensile strength σu and Brinell hardness HB are known for some groups of steels. These relations represented in the form of formulas, tables, or plots make it possible to quickly estimate σu from HB without fabricating specimens. Therefore, they are necessary during input control of blanks, treatment of steels by various methods, diagnostics of steel state after long-term service, or reductive heat treatment, and in other cases. There are very limited data on such relations for nonferrous metals and alloys; however, there are tables, which give the values of σu and HB for some alloys based on aluminum, copper, and titanium. When establishing more general and correct σu–HB relations for various structural materials (ferrous and nonferrous alloys), it is appropriate to relate σu to the maximum Brinell hardness, which enables one to obtain a general relation for ferrous and nonferrous alloys. To determine the maximum Brinell hardness, it is proposed to use depth-sensing indentation with recording the load F–indenter displacement α indentation diagram with its subsequent conversion to the unrecovered Brinell hardness HBt–relative indentation depth t/R diagram. The maximum hardness (HB)max can be easily determined from the maximum of the HBt–t/R diagram. This report presents the results of tests, in which σu and have been determined for many steels, aluminum, magnesium, and titanium alloys, and a directly proportional relation between these mechanical characteristics is found. [ABSTRACT FROM AUTHOR]

We conducted large-scale molecular dynamics (MD) simulations of shock wave propagation and spallation in amorphous polyurethane and polyurea. First, we computed the shock Hugoniot of the polymers using the multiscale shock technique and compared them with available experimental data to establish the upper limit of the shock pressure that can be accurately modeled using a non-reactive interatomic force field. Subsequently, we simulated shock wave propagation in the polymers, varying the shock particle velocity from 0.125 km/s to 2 km/s. A remarkable similarity in the shock behavior of polyurethane and polyurea was observed. The spall strength of each sample was computed by two methods: (a) the indirect method (based on the free surface velocity history)--accessible in experiments and (b) a direct method (based on the atomic stresses in the region of spallation)--accessible only through MD. The results reveal that the tensile strength computed from the indirect method is consistently smaller than the value obtained from the direct method. Moreover, the strength computed from the indirect method shows a noticeable agreement with the fracture nucleation stress. Our results provide novel molecular-level insights into the spallation mechanisms of amorphous polymers, which could facilitate the design of polymers for structural barrier applications. [ABSTRACT FROM AUTHOR]

Aluminium and its alloys are lightweight, corrosion-resistant, affordable and high-strength material and find wide applications in shipbuilding, automotive, constructions, aerospace and other industrial sectors. In applications like aerospace, marine and automotive industries, there is a need to join components made of different aluminium alloys, viz. AA6061 and AA5083. In this study friction stir welding (FSW) is used to join dissimilar plates made of AA6061-T6 and AA5083-O. The effect of varying tool pin profile, tool rotation speed, tool feed rate and tilt angle of the tool has been investigated on the tensile strength and percentage elongation of the welded joints. Box-Behkan design, with four input parameters and three levels of each parameter has been employed to decide the set of experimental runs. The regression models have been developed to investigate the influence of welding variables on the tensile strength and elongation of the welded joint. It is revealed that with the increase in welding parameters like tool rpm, tool feed rate and tilt angle of the tool, both the mechanical properties increase, reach a maximum level, followed by a decrease with further increase in the value of parameters. Amongst different types of tool pin profiles used, the FSW tool having straight cylindrical (SC) pin profile is found to yield the maximum strength and elongation of the welded joint for different combinations of welding parameters. Multiple response optimization indicates that the maximum UTS (135.83 MPa) and TE (4.35%) are obtained for the welded joint fabricated using FSW tool having SC pin profile, tilted at 1.11° and operating at tool speed and feed rate of 1568 rpm and 39.53 mm/min., respectively. [ABSTRACT FROM AUTHOR]

Welding metal alloys with dissimilar melting points makes conventional welding processes not feasible to be used. Friction welding, on the other hand, has proven to be a promising technology. However, obtaining the welded joint's mechanical properties with characteristics similar to the base materials remains a challenge. In the development of this work, several of the machine learning (ML) regressors (e.g., Gaussian process, decision tree, random forest, support vector machines, gradient boosting, and multi-layer perceptron) were evaluated for the prediction of the ultimate tensile strength (UTS) in joints of AISI 1045 steel and 2017-T4 aluminum alloy produced by rotary friction welding with laser assistance. A mixed design of experiments was employed to assess the effect of the rotation speed, friction pressure, and laser power over the UTS. Furthermore, the response surface methodology (RSM) was employed to determine an empirical equation for predicting the UTS, and contours maps determine the main interactions. A total of 48 specimens were employed to train the regressors; the 5-fold cross-validation methodology was used to find the algorithm with greater precision. The gradient boosting regressor (GBR), support vector regressor (SVR), and Gaussian processes regressors present the highest precision with a less than 3% percentage error for the laser-assisted rotary friction welding process. The GBR and SVR capability exceed the RSM's accuracy with a coefficient of determination (R2) greater than 90.9 versus 83.2%, respectively. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of pre-heating a dual-polymerized adhesive and a dual-polymerized core build-up resin composite on their dentin micro-shear bond strength (µSBS), degree of conversion (DC%) and ultimate tensile strength (UTS). For µSBS, 45 human molars were divided into 9 groups (n = 5) according to two factors: (1) Adhesive temperature (25 °C/32 °C/40 °C) and 2- Resin composite temperature (25 °C/32 °C/40 °C). Dual-polymerized adhesive (Futurabond U/FBU) was applied over occlusal dentin at each temperature following the manufacturer's instructions. Four dual-polymerized composites (Rebilda DC/RDC, VOCO) micro-cylinders (1.2 mm diameter × 1 mm height) were built-up over each dentin disc, after being pre-heated at each temperature. After storage (48 h/37 °C), µSBS testing was run at a crosshead speed of 1 mm/min. DC% of FBU/RDC was evaluated at each temperature after 48 h using FTIR. Hourglass-shaped specimens were fabricated from both materials at each respective temperature and pulled apart to evaluate UTS after 48 h storage. Data were analyzed by ANOVA/Tukey's test/Pearson's correlation (p = 0.05). Neither adhesive/composite temperature nor their interaction had a significant effect on µSBS. No significant difference in µSBS between groups, except within 40 °C FBU. Predominant failure mode was a mixed type. No significant difference in DC% of FBU groups. RDC at 40 °C had significantly higher DC% than 25 °C. No significant difference in UTS of FBU and RDC groups. Application of both dual-polymerized adhesive and resin composite at 40 °C seemed to reduce µSBS. Raising the temperature to 40 °C improved DC% of resin composite, with no effect on adhesive. Pre-heating did not influence the UTS of both materials. [ABSTRACT FROM AUTHOR]

The present work aims to explore the effects of the alloying elements (Si, Bi, Sb, Ni, and Co) and solidification rates (V) on the microstructural morphology, microhardness, ultimate tensile strength and electrical resistivity of Al-Cu based eutectic alloys by Bridgman-type solidification apparatus, metallographic observation, scanning electron microscopy, microhardness testing, tensile testing and four-point probe testing. Firstly, the Al-33 Cu-2X (wt.%) samples were produced by using metals of high purity (> 99.95 %) in the vacuum and hotfilling furnaces; these alloys were unidirectionally solidified under different solidification rates, V (8.28-167.08 µm s-1) and constant temperature gradient, G (average 8.50 K mm-1). Secondly, metallographic examination and measurement processes: lamellar spacings (1), microhardness (HV), ultimate tensile strength (UTS) and electrical resistivity (1) were measured and expressed as functions of V. It has been found that the addition of the alloying elements (AE) content in Al-Cu eutectic as well as increasing of V lead to a decrease of lamellar spacings. On the contrary, the values of HV, UTS, and increase with increasing V values and the addition of alloying elements. Relationships between a-V, a-HV, a-UTS (s) and a-1 were found by regression analysis, and the results found in this research were compared with the previous similar studies. [ABSTRACT FROM AUTHOR]

Aluminum based composite are getting a vast scope nowadays because of its high properties and availability as fit large industrial development. (AMC) Aluminum metal-matrix composites is new engineering materials which contains two or more materials with different properties one being a metal from Aluminum and other may be metal, ceramic, glass reinforced materials. So in This present article We try to prepare hybrid composite materials based on aluminum alloy (AA6063) and reinforcement it by shared particles having size of micron of Alumina (7.5 wt%) and Graphite particles are added in specific countrified parentage (2.5, 5, 7.5, 10 wt%) by stir casting technique to obtain hybrid Aluminum Which having the improving mechanical properties,Heat treatment (solution heat treatment-artificial aging) are carried out on all samples,After that inspections and mechanical tests have be done on all reinforcement samples, The results of Scanning electron microscope have shown uniform distribution of hybrid reinforced particles in matrix alloy and hybrid reinforced Aluminum alloy successfully prepared using stir casting method. The results of tests have shown The Impact toughness,, and Ultimate tensile strength were determined, with the addition of reinforcement the properties and effect of Precipitation hardening Heat treatment are improved compared to the parent metal Aluminum (6063) alone. [ABSTRACT FROM AUTHOR]

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Strength and hardness of metallic materials are reported to correlate in a specified form. Among various equations, yield strength is generally converted from Vickers hardness (HV) via a three‐time relation due to the simple and nondestructive nature of hardness testing. Herein, a through literature review is made and data of strength and HV for face‐centered cubic (FCC) and body‐centered cubic (BCC) high‐entropy alloys (HEA) are collected. The yield strength and HV visibly deviate from the three‐time relation, but the ultimate tensile strength and HV roughly follow the three‐time relation. New linear relationships, which are universally applied to convert HV to yield strength and ultimate tensile strength, are proposed. [ABSTRACT FROM AUTHOR]

The instrumented indentation test (IIT) is an attractive non-destructive testing technique. Determining accurate strength properties of steel using IIT is still challenging. In this paper, a new methodology is proposed to acquire the yield and ultimate tensile strength from a single IIT. This method extracts true stress-strain curves from IIT results. Acquired stress-strain curves indicate that the initial yield stress is not repeatable. This is caused by the inhomogeneous deformation of IIT specimens. Based on the obtained true stress-stain curves, corresponding yield strength, and ultimate tensile strength are calculated through theoretical derivation. The results show that the strength has a convergent tendency. On basis of this phenomenon, the strength is determined with an extrapolating method. Finally, the strength properties of Q345R are investigated to verify the reliability of this method. It is found that the strength determined from IIT and conventional tensile tests shows good agreement. The proposed method is effective in predicting strength properties from a single instrumented indentation test. [ABSTRACT FROM AUTHOR]

In this exploration study, friction stir welding of Al-Li 8090 alloys has been accomplished for the optimization of process parameters for determined joint strength. Taguchi's L9orthogonal array (OA) has been used for different three parameters-tool rotational speed, tool traverse speed, and dwell time. To optimize, multi-response had been carried out through Taguchi's-based design of expert. It has been designed for all three responses--ultimate tensile strength, and micro hardness, microstructure. Thermal behaviour analysis shows the temperature variation during friction stir welding at different parameters. Analysis of variance has been used as a tool for obtaining DOE-OA to determine the significant process parameter. Tool traverse speed and dwell time has been predicted the two utmost significant parameters which influence extreme quality features of joint by friction stir welding. Validation of the probable value obtains by confirmation experiments at optimal sets shows the worthy agreement with the values of the experimental outcomes. [ABSTRACT FROM AUTHOR]

In the present study, Al6061/Al 2 O 3 composite coating was produced to repair the notched Al7075 substrate by cold spraying (CS) and laser assisted cold spray (LACS) technology. The preparation process and parameter selection of high-performance coating were discussed by combining simulation and experiment. Results showed that the LACS experiment guided by simulation results achieved high-quality bonding of single particle with the substrate. In addition, the tensile strength of samples repaired by LACS recovered to the level of original substrate, and the ductility was significantly higher than that of CS process. This is attributed to the introduction of laser irradiation heating, which improves the plastic deformation ability of particles and produces atomic-level metallurgical bonding between the particles. This study provides a possibility for the repair and remanufacture research of high-quality components, and has great development potential in future research. • The tensile properties of notched hard Al alloy were restored through LACS. • The deposition mechanism of single particle under laser heating was studied. • Laser heating causes atomic level metallurgical bonding at the interface. [ABSTRACT FROM AUTHOR]

Strength, toughness, and stress corrosion resistance are critical properties of aluminum alloys for high-end equipment manufacturing. Unfortunately, the situation of complex alloy composition, diverse aging systems, and conflicting property relationships hinder the synchronous enhancement of three properties. Here, we proposed an interpretable machine learning design strategy for high-end aluminum alloy. The critical intrinsic factors and explicit laws of elements affecting the ultimate tensile strength (UTS), fracture toughness (K IC), and stress corrosion sensitivity factor (ISSRT) of alloys were excavated: The elements with large number of electrons in d-valence electron orbitals, high boiling point, and low nuclear electron distance help enhance the UTS; The elements with low density and minimized difference in first ionization energy with aluminum help improve the K IC ; The elements with high diffusion activation energy in aluminum and high corrosion potential in seawater help reduce the ISSRT. Based on the above findings, three microalloying elements of Ti, Cr, and Zr, which have the remarkable combined effect of enhancing synchronously the three properties, were selected, and a new advanced aluminum alloy Al-10.50Zn-2.31Mg-1.56Cu-0.09Ti-0.15Cr-0.10Zr was designed. The UTS, K IC, and ISSRT were 760 ± 4 MPa, 34.9 ± 0.3 MPa·m1/2, and 13.3 % ± 1.7 %, respectively, after RRA treatment. Microstructure analysis revealed that the new alloy had almost no micron secondary phase after RRA treatment, reducing the sites for pitting and cavity formation. The addition of Ti, Cr, and Zr formed dispersoids Al 18 (Cr,Ti) 2 Mg 3 and Al 3 Zr, which contributed to the synchronous improvement of strength, toughness, and stress corrosion resistance. The high-volume fraction of precipitates significantly enhanced the strength of the alloy. [Display omitted] [ABSTRACT FROM AUTHOR]

Concrete breakout (CB) failure is the most common failure mode for studs in tension. Based on the Griffith's strength theory, Mohr's circle method, and mechanics of materials, the breakout cone failure model and failure mechanism of the CB mode are analyzed; the shape of the breakout cone is hyperboloid cone, and the failure of CB mode is due to the concrete tensile failure. The classic concrete capacity design (CCD) method only applies to normal concrete (NC) substrate. To predict ultimate tensile strength ( N b) of the CB mode for a wider range of concrete properties, including high-strength concrete (HSC), ultra-high performance concrete (UHPC), engineered cementitious composite (ECC), etc., a new "Hyperboloid Cone Model" is proposed, which is based on the original form of CCD method and the Griffith's strength theory. The comparison between the experimental and predicted N b for the studs in various substrates (NC, HSC, UHPC, and ECC) from past studies shows that the prediction of the proposed model on N b is more accurate with significantly smaller variances compared to CCD method; the average ratio of the experimental to calculated value of the proposed model and the CCD model is 0.974 and 1.138, respectively, while the coefficient of variance of them is 11.27% and 40.44%, respectively. • The behavior of CB mode is analyzed through the Griffith's strength theory. • The morphology assumption of anchors in CB mode is a hyperboloid cone. • A Hyperboloid Cone Model suitable for concrete of various properties is established. • The Hyperboloid Cone Model is in good agreement with the actual tests. [ABSTRACT FROM AUTHOR]

The study investigated the anti-correlation between thermal diffusivity and Ultimate Tensile Strength (UTS) in Usibor® 1500 steel. The non-destructive pulsed laser spot thermography technique was used to analyze fifteen boron steel specimens with varying bainite/martensite phase percentages, while the UTS was measured through uniaxial tensile tests. A 23 % thermal diffusivity difference was found between fully martensitic and fully bainitic structures, with UTS varying by around 90 %. The strong anti-correlation was confirmed (Spearman coefficient −0.98) and an empirical power-law equation was derived to estimate UTS based on thermal diffusivity variations. The approach showed an R-squared value over 0.84, providing a non-destructive thermographic procedure for UTS estimation in Usibor® 1500 steel, offering valuable material property insights. • New non-destructive method for estimating the ultimate tensile strength in steel. • An anti-correlation between thermal diffusivity and ultimate tensile strength. • Measurement of thermal diffusivity to estimate mechanical resistance in Usibor 1500. • Evaluation of the Al–Si coating on thermal diffusivity measurements in steel. • Empirical relations between thermal diffusivity and UTS in Usibor® 1500. [ABSTRACT FROM AUTHOR]

Cadmium oxide doped zinc oxide (CdO–ZnO) nanoparticles were synthesized by solution combustion technique. CdO–ZnO nano particles were used as fillers and their concentration ranged between 0.5% to 2.5% by weight in polyvinyl alcohol (PVA) films. The effect of nano filler concentration on structural, electrical and mechanical properties was investigated. Dielectric constant values decreased upto 1.24 GHz frequency, between 1.24 to 3 GHz frequency range a slight increase in dielectric constant was observed. At frequencies above 500 kHz increase in AC conductivity and loss tangent of the polymer nanocomposites were observed. Enhanced mechanical properties were observed with increase in dopant concentration. A significant increase of 152.65% in film toughness, 113.58% increase in elastic modulus and 83.10% increase in ultimate tensile strength was observed at 2.5 wt% concentration of CdO–ZnO in PVA film as compared to pristine PVA film, which makes CdO–ZnO a desirable reinforcing material for nanocomposites.

The present study focuses on improving the ultimate tensile strength of friction stir welded carbon steel (AISI 1018). The effect of the process parameters (welding speed, tool RPM, and shoulder diameter) on the response parameters (ultimate tensile strength, percentage elongation and percentage reduction in area) were studied. Response surface methodology was used to develop the mathematical model for response parameters, and the adequacy of the model was checked using analysis of variance (ANOVA). The welding speed and tool RPM were found to affect the ultimate tensile strength significantly. The percentage elongation was affected only by welding speed. The percentage reduction in the area was affected by welding speed and shoulder diameter. The microstructure and microhardness of the weld have been studied and reported in the study. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM) is an additive manufacturing technology to fabricate three-dimensional prototypes with complex geometries. The ultimate tensile strength and surface finish of the parts produced by FDM process are strongly related to the fabrication process parameters. So it is necessary to identify the optimal process parameters to improve the ultimate tensile strength and surface finish of the part. FDM process has been influenced by many process parameters and the process parameters such as raster angle, infill pattern and build orientation have been considered in this study to determine their influence on the response parameters such as ultimate tensile strength and surface roughness of Polylactic Acid (PLA)-Acrylonitrile Butadiene Styrene (ABS) blend. In this work, an experimental study has been validated using the response surface methodology and influence of the process parameters on response parameters has been analyzed using analysis of variance (ANOVA) method. Scanning Electron Microscope (SEM) images have been used to study the microstructure of the specimen at the fracture interface. The result has shown that infill pattern is the significant factor affecting the ultimate tensile strength. Surface roughness of the specimen has been found influenced by the build orientation followed by the infill pattern and raster angle. [ABSTRACT FROM AUTHOR]

The development and subsequent rupture of atherosclerotic plaques in human carotid arteries is a major cause of ischaemic stroke. Mechanical characterization of atherosclerotic plaques can aid our understanding of this rupture risk. Despite this however, experimental studies on human atherosclerotic carotid plaques, and fibrous plaque caps in particular, are very limited. This study aims to provide further insights into atherosclerotic plaque rupture by mechanically testing human fibrous plaque caps, the region of the atherosclerotic lesion most often attributed the highest risk of rupture. The results obtained highlight the variability in the ultimate tensile stress, strain and stiffness experienced in atherosclerotic plaque caps. By pre-screening all samples using small angle light scattering (SALS) to determine the dominant fibre direction in the tissue, along with supporting histological analysis, this work suggests that the collagen fibre alignment in the circumferential direction plays the most dominant role for determining plaque structural stability. The work presented in this study could provide the basis for new diagnostic approaches to be developed, which non-invasively identify carotid plaques at greatest risk of rupture. Mechanical characterisation of the atherosclerotic plaque cap is of utmost importance for understanding the mechanisms that govern the rupture strength of this tissue in-vivo. Studies has shown that plaque tissue is heterogenous and comprises of many structural components, each of which exhibits a varying mechanical response. However, rupture generally is located to the plaque cap, whereby the stress exerted on this location exceeds its mechanical strength causing failure. This work shows, for the first time, that the underlying collagen fibre architecture of carotid plaque caps governs their strength and stiffness. This study shows that plaque caps with collagen fibres aligned in the predominately circumferential direction experience higher stresses and lower strains before failure while those with predominately axial fibres display the opposite trend. Furthermore, total collagen content was found not to play a dominant role in determining the mechanical response of the tissue. The present study provides critical insights into human atherosclerotic plaque tissue mechanics and offers clinically relevant insights for mechanically sensitive imaging techniques, such as strain-based ultrasound or MRI. [Display omitted] [ABSTRACT FROM AUTHOR]

A copula-based approach is used to estimate the dependence among three lumber strength properties: modulus of elasticity (MOE), modulus of rupture (MOR), and ultimate tensile strength (UTS). MOR and UTS are destructive measurements so they cannot be obtained simultaneously for lumber specimens. The dependence modeling is possible under an appropriate experimental design with i) a shoulder group for rupture, ii) a shoulder group for tension, and iii) other groups proof loaded in either the rupture or tension mode with survivors tested to failure in the mode that was not initially tested. With a fitted copula model based on an assumption of no damage due to the proof loading procedure, we conclude that there is a strong dependence between MOR and UTS conditioning on MOE. To assess the “no damage assumption,” a graphical method with simulated data from the fitted copula model is used. It suggests that there may be some damage to the lumber specimens due to proof loading, especially for weaker lumber specimens. Information from the dependence model can potentially help reduce monitoring costs in the lumber industry.

In this research work the machining waste white cast iron powder (WCI) is introduced in the age hardenable Al7075 alloy matrix with the objective of enhancing the tensile properties by well-known age hardening treatment. This material holds good in light duty dies where in the strength-related characteristics improvement is the order of the day. In view of this the effect of aging kinetics on the hardness pattern and tensile strength of stir cast Al7075-white cast iron (WCI) particulate reinforced composites in as cast and peak aging conditions is investigated. The composite is cast by two step liquid stir casting route. During precipitation hardening heat treatment, reinforcement weight percentage (internal variable) and aging temperature (external variable) are considered to be the major strengthening variables. To understand the nature of failure in tensile study, fracture surface analysis is carried out using SEM. The experimental values revealed that there is a substantial enhancement in the desired properties during the precipitation hardening treatment, if the strengthening variables are properly controlled. Hardness and tensile strength of the composite have increased with increase in weight percentage of reinforcement and reduction in aging temperature. Maximum hardness and tensile strength are observed when Al7075 alloy is reinforced with 6 weight% of WCI, aged at 100ᴼC. SEM images of tensile fracture surface exhibits abundant cup-like depressions or dimples as well as river patterns indicating mixed mode of failure. The equally aligned facets (dendrites) present in the peak-aged fracture surfaces is the evidence for the attainment of optimum (peak) aging condition. The aim of the present research work is to improve the hardness-related properties by the combined effect of precipitation of secondary phases (intermetallics) through aging treatment and dispersion strengthening by the introduction of hard reinforcement WCI.

In this study, Ti-30Mo-nTiC (0, 0.5 wt.%) and Ti-30Mo-0.5TiC-xZr (0, 4, 8, 12 wt.%) alloys were prepared using the powder metallurgy process with the addition of Zr at different rates. The effect of TiC and Zr additions on the microstructure and mechanical properties of the Ti-30Mo alloys were investigated, respectively. The results demonstrated that the addition of 0.5 wt.% TiC significantly improved the density, tensile strength and elastic modulus. The ultimate tensile strength, elongation and elastic modulus of the Ti-30Mo-0.5TiC alloy were determined to be 825 MPa, 7.3% and 112 GPa, respectively. For Ti-30Mo-0.5TiC-xZr alloys, the addition of Zr (8 wt.% or less) results in alloys having a high relative density (>98%), with the density of the alloy decreasing significantly when the Zr content is 12 wt.%. As the Zr content increases, the β phase lattice constant also increases along with the amount of carbide aggregation. This leads to a decrease in the alloy strength, with an increase in the alloy hardness. During high temperature tensile testing at 600 °C, the Ti-30Mo-0.5TiC alloy still had suitable mechanical properties, with its ultimate tensile strength and elongation being 472 MPa and 12.8%, respectively.

Currently, the growth of material data from experiments and simulations is expanding beyond processable amounts. This makes the development of new data‐driven methods for the discovery of patterns among multiple lengthscales and time‐scales and structure‐property relationships essential. These data‐driven approaches show enormous promise within materials science. The following review covers machine learning (ML) applications for metallic material characterization. Many parameters associated with the processing and the structure of materials affect the properties and the performance of manufactured components. Thus, this study is an attempt to investigate the usefulness of ML methods for material property prediction. Material characteristics such as strength, toughness, hardness, brittleness, or ductility are relevant to categorize a material or component according to their quality. In industry, material tests like tensile tests, compression tests, or creep tests are often time consuming and expensive to perform. Therefore, the application of ML approaches is considered helpful for an easier generation of material property information. This study also gives an application of ML methods on small punch test (SPT) data for the determination of the property ultimate tensile strength for various materials. A strong correlation between SPT data and tensile test data was found which ultimately allows to replace more costly tests by simple and fast tests in combination with ML. [ABSTRACT FROM AUTHOR]

In this paper, nanoscale mechanical properties and failure behavior of graphene with Stone-Wales defect concentration were investigated using molecular dynamics simulations with the latest ReaxFFC-2013 potential that can accurately capture bond breakages of graphitic compounds. The choice of interatomic potential plays an essential role in capturing the deformation mechanism accurately. Stable configuration of two-dimensional graphene experiences out-of-plane deformation leading to ripples and wrinkles in graphene. It is observed that the mechanical properties such as Young's modulus, ultimate tensile strength, and the fracture strain are dependent on the out-of-plane deformation, temperature, defect concentration, defect orientation, defect layout and loading configuration. It is observed that the post transient phase non-homogenous ripples and wrinkles influence the mechanical properties at low and high defect concentrations, respectively. [ABSTRACT FROM AUTHOR]

To determination of equal-channel angular pressing(ECAP) process on the stress-strain behavior of steel core of steel/copper bi-metal and also the effect of Cu-shell thickness on the created surface stretch during ECAP, the bimetallic samples composed of steel rods with 8 mm diameter and copper shells with 0.75 mm thickness are prepared. Both bimetallic samples and steel rods with 9.5 mm are subjected to consecutive ECAP process using a die with an inner angle 90° and an outer curvature corner angle of 30o. The applied load and punch displacement are recorded during samples passing through an ECAP die. The tensile testing is carried out on both the initial and ECAPed series. Moreover, the dependence of surface stretch to diameters, shell thickness, and strength properties of constituents of core/shell bimetallic rods is analytically modeled. Then, the finite element method (FEM) is used to investigate the effect of Cu-shell thickness. The obtained results revealed that the ultimate tensile strength of the bimetallic core and steel rods are improved by approximately 60% and 108% by ECAP deformation, respectively. The applied punch load for passing of bimetallic sample through an ECAP die is 54% less than the ones for steel rod. According to the FEM results, the maximum value of surface stretch is linearly decreased with increasing the thickness of the copper shell. The obtained results show a good agreement between the analytical model and the FEM approach. [ABSTRACT FROM AUTHOR]

Present study describes the effect of forge application under consideration of friction time on metallurgical and mechanical properties of friction welded joint for AISI 316. Direct drive friction welding (DDFW) has been utilized to obtain welded joints. Three friction times (6.5 s, 8.5 s and 10 s) with two directions for this study were used; the first direction was achieved by forge phase elimination and the second was performed under forge phase application. Macro-microstructure for welded joint, microhardness across the axial direction, tensile tests and tensile fracture morphology were investigated. As a conclusion, flash formation was decreased about 30% without forge compared to forge application. Thermo-mechanically affected zone (TMAZ) was extended in 8 mm at the interface without forge and highly plastically deformed zone (HPDZ) can be found at the interface after forge application. At shorter friction time for the two directions, ultimate tensile strength (UTS) and ductility were revealed closer to AISI 316. Hence, all tensile fractures were occurred adjacent to the interface at TMAZ, except in the shorter friction time after in forge application, the fracture was happened at the base metal, and that was confirmed with the fracture morphology which has the same character of AISI 316. [ABSTRACT FROM AUTHOR]

Tensile testing is an essential experiment to assess the mechanical integrity of musculoskeletal soft tissues, yet standard test methods have not been developed to ensure the quality and reproducibility of these experiments. The ASTM International standards organization has created tensile test standards for common industry materials that specify geometric dimensions of test specimens (coupons) that promote valid failures within the gage section (midsubstance), away from the grips. This study examined whether ASTM test standards for plastics, elastomers, and fiber-reinforced composites are suitable for tensile testing of bovine meniscus along the circumferential fiber direction. We found that dumbbell (DB) shaped coupons based on ASTM standards for elastomers and plastics had an 80% and 60% rate of midsubstance failures, respectively. The rate of midsubstance failures dropped to 20% when using straight (ST) coupons based on ASTM standards for fiber-reinforced composites. The mechanical properties of dumbbell shaped coupons were also significantly greater than straight coupons. Finite element models of the test coupons revealed stress distributions that supported our experimental findings. In addition, we found that a commercial deli-slicer was able to slice meniscus to uniform layer thicknesses that were within ASTM dimensional tolerances. This study provides methods, recommendations, and insights that can advance the standardization of tensile testing in meniscus and other soft fibrous tissues. [ABSTRACT FROM AUTHOR]

In this research work the machining waste white cast iron powder (WCI) is introduced in the age hardenable Al7075 alloy matrix with the objective of enhancing the tensile properties by well-known age hardening treatment. This material holds good in light duty dies where in the strength-related characteristics improvement is the order of the day. In view of this the effect of aging kinetics on the hardness pattern and tensile strength of stir cast Al7075-white cast iron (WCI) particulate reinforced composites in as cast and peak aging conditions is investigated. The composite is cast by two step liquid stir casting route. During precipitation hardening heat treatment, reinforcement weight percentage (internal variable) and aging temperature (external variable) are considered to be the major strengthening variables. To understand the nature of failure in tensile study, fracture surface analysis is carried out using SEM. The experimental values revealed that there is a substantial enhancement in the desired properties during the precipitation hardening treatment, if the strengthening variables are properly controlled. Hardness and tensile strength of the composite have increased with increase in weight percentage of reinforcement and reduction in aging temperature. Maximum hardness and tensile strength are observed when Al7075 alloy is reinforced with 6 weight% of WCI, aged at 100ᴼC. SEM images of tensile fracture surface exhibits abundant cup-like depressions or dimples as well as river patterns indicating mixed mode of failure. The equally aligned facets (dendrites) present in the peak-aged fracture surfaces is the evidence for the attainment of optimum (peak) aging condition. The aim of the present research work is to improve the hardness-related properties by the combined effect of precipitation of secondary phases (intermetallics) through aging treatment and dispersion strengthening by the introduction of hard reinforcement WCI. [ABSTRACT FROM AUTHOR]

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Friction Stir Welding (FSW) is a solid-state joining process for metals, non-metals and polymers. It is carried out with the help of a specially designed, non-consumable tool. The heat required, for creating a softened region at the faying surfaces, is generated by rotation of tool against the work piece material. Being a solid-state welding process, it offers several advantages like inducing minimum effect on the mechanical properties of base material, reduced shrinkage and distortion, no spatter or Ultra Violet (UV) radiations etc. However, developing a sound weld requires an appropriate combination of several process parameters e.g. the design of tool, its rotational and traversing speeds etc. To substantiate this aspect, an approach based on Response Surface Methodology (RSM) is presented during this paper that optimizes the combination of process parameters while investigating their effect on the mechanical properties of a friction stir welded butt joint configuration of Polycarbonate. To minimize the total number of combinations a Central Composite Rotatable Design (CCRD) is used with three factors and two levels. The results have shown that the butt joints fabricated at a traverse speed of 14 mm/min, rotational speed of 1700 RPM and with simple cylindrical conical tool geometry yielded the maximum ultimate tensile strength of 51.299 MPa. [ABSTRACT FROM AUTHOR]

This paper deals with the experimental analysis of Friction Stir Welding (FSW) of AA1100 aluminum alloy joined by means of a square pin tool. During the process, temperature measurement has been done by means of K-type thermocouples and it has been noticed that the temperature in the advancing side (AS) of the weld is about 20-25 °C higher than its retreating side (RS). The ultimate tensile strength (UTS) of the welded specimen is increased by 20% of the parent material due to the uniform dispersion of silicon particles present within the base material. Microstructural observations revealed finely arranged equiaxed grains in the nugget region of the weld. X-ray diffraction results showed the formation of alumina (Al2O3) in the weld nugget due to high heat generation and exposure to atmospheric oxygen during welding. Residual stress measurement exhibited a M-shaped distribution. The samples joined at low travel speed and high tool rotational speed showed compressive residual stress in the joint region. Residual stress of the material lying below the tool shoulder is found to be tensile in nature. Also, it has been noticed that the residual stress in the AS is superior in magnitude than the RS of the weld specimen. [ABSTRACT FROM AUTHOR]