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This research involves stress-strain analysis in poly(methyl methacrylate) (PMMA) octagonal shape compressed by hydraulic system. The observation of uniaxially stressed samples was carried out using reflection photoelasticity technique. The results of fringe order number and principal stress angle were used to determine stress and strain distribution in the samples by shear difference method. It was found that high stress-strain region was close to the contact point where compressive force was applied but it was zero at the edge of the samples. The area of high strain region increased as the magnitude of force was increased but it decreased as the dimension of octagonal shape was increased. [ABSTRACT FROM AUTHOR]

This study investigated the effects of Pb 2 O 3 nanoparticles on the thermal, mechanical, and shielding properties of epoxy resin, liquid silicone rubber, and polyvinyl chloride composites which have been proposed as efficient substitutes for traditional lead-based materials for shielding gamma and X-ray radiations. The Pb 2 O 3 nanoparticles were synthesized using a low-cost electrochemical method, characterized by XRD and SEM analysis, and uniformly dispersed in the polymer matrix by casting technique. The mechanical and thermal properties of the samples were investigated by stress-strain and TGA analysis, and the effectiveness of Pb 2 O 3 in improving the radiation shielding capabilities of the polymers was investigated by analyzing parameters such as the mass attenuation coefficients and the half-value layer factor for gamma rays. The results showed that the addition of Pb 2 O 3 nanoparticles had no adverse effect on the thermal stability of polyvinyl chloride (PVC) composites; at the same time, it decreased the thermal stability and increased the weight loss of Epoxy Resin (ER) and Liquid Silicon Rubber (LSR) composites. The nanocomposites had higher tensile strength and modulus of elasticity than the original polymer, and their shielding properties improved with increasing nanofiller content. This study provides insights into modifying the properties of composites using fillers and polymers to improve their properties for various applications. [Display omitted] • Different epoxy resin, silicone, and PVC-based Pb 2 O 3 nano composites (namely 10, 20, 30, and 40 wt%) were produced. • Low-priced electrochemical synthesis method was used to synthesize Pb 2 O 3 nano particles. • Thermal, mechanical, and shielding properties of constructed nano composites were experimentally assessed. • Findings: PVC thermal stability unaffected by Pb2O3 nanoparticles. ER and LSR composites' stability reduced; weight loss increased. • Nanocomposites surpassed original polymer in strength, elasticity, and shielding with increased nanofiller content. [ABSTRACT FROM AUTHOR]

A deep understanding of the motion and the intensities of forces endured by the fruits overtime during the various handling processes is necessary if improvements are to be made in the handling systems or related tools. The finite element method (FEM) has been used to investigate the effect of mechanical loading on fruit before developing a prototype of the intended design. Simulation tests were performed to visualise the time-dependent deformation behaviour. Various studies have been reported on the use of FE for studying the effect of compression and drop forces on fruits. However, to the best of the knowledge of the authors, the application of finite-element analysis in fruit mechanics has not been summarized yet. This review is concerned with establishing the introductory concept of FEM for evaluating fruit response under the static and dynamic loading. The FE equations were formulated based on the stress-strain constitutive equations. The review summarises the application of FEM for fruit stress-strain analysis. A brief description of the fundamentals and the existing models that have been developed to cope with problems of fruit mechanics are reported. This paper provides a review of the main FEM studies and a comparison between different types of stress analysis as well as outlining the potential use of FEM for future reference. This review can become an appropriate, timely and beneficial reference for any relevant follow-up research for the assessment of the quality of agricultural produces. • Physical and mechanical properties of fruits towards various type of impact loadings. • Introductory concept of finite element (FE) method for fruit response on static and dynamic loading. • Application of FE method for fruit stress-strain analysis. [ABSTRACT FROM AUTHOR]

A coaxial extrusion printhead was designed for 3D printing of pectin-based food simulants in which the inner flow is the food-ink and the outer a CaCl 2 crosslinking solution. A series of cubic-shaped objects was successfully 3D printed by changing the printing parameters including the food-ink composition, the layer height, and the rate and CaCl 2 concentration of the outer flow. The printed objects did not necessitate any incubation post-treatment because the gelation of the food-ink occurred during the printing. The mechanical properties of the printed object were correlated to their final Ca 2+ concentration which can be controlled by the rate and CaCl 2 concentration of the outer flow. A predictive model was established for determining the printing settings to print 3D objects with a priori defined texture. The layer height was recommended to be set in function of the food-ink swelling behavior. Finally, we compared objects printed by coaxial and simple extrusion methods. The compared objects had similar Young's moduli but their other properties including volume and final Ca 2+ concentration, were considerably impacted by the printing method. [ABSTRACT FROM AUTHOR]

We developed and evaluated a solvent-free injection molding (IM) coating technology that could be suitable for continuous manufacturing via incorporation with IM tableting. Coating formulations (coating polymers and plasticizers) were prepared using hot-melt extrusion and screened via stress-strain analysis employing a universal testing machine. Selected coating formulations were studied for their melt flow characteristics. Tablets were coated using a vertical injection molding unit. Process parameters like softening temperature, injection pressure, and cooling temperature played a very important role in IM coating processing. IM coating employing polyethylene oxide (PEO) based formulations required sufficient room humidity (>30% RH) to avoid immediate cracks, whereas other formulations were insensitive to the room humidity. Tested formulations based on Eudrajit E PO and Kollicoat IR had unsuitable mechanical properties. Three coating formulations based on hydroxypropyl pea starch, PEO 1,000,000 and Opadry had favorable mechanical (<700 MPa Young’s modulus, >35% elongation, >95 × 10 4 J/m 3 toughness) and melt flow (>0.4 g/min) characteristics, that rendered acceptable IM coats. These three formulations increased the dissolution time by 10, 15 and 35 min, respectively (75% drug release), compared to the uncoated tablets (15 min). Coated tablets stored in several environmental conditions remained stable to cracking for the evaluated 8-week time period. [ABSTRACT FROM AUTHOR]

Fatigue life prediction of notched components requires accurate local stresses and strains at notch areas. Researchers have developed a number of approximation methods to estimate local elasto-plastic stress and strain responses on the basis of elastic stress/strain results. The most two common methods are known as the Neuber rule and the equivalent strain energy density (ESED) method. It has been presented that the Neuber rule has a tendency to overestimate notch elasto-plastic strains and stresses while the ESED method tends to underestimate notch elasto-plastic strains and stresses. These drawbacks are attributed to the fact that the original Neuber rule was developed for notched bodies under pure shear loading, but the Neuber rule is applied to other multiaxial loadings where the present stress state can significantly vary from the pure shear stress state. Therefore, analytical approximation model based on the deviatoric form of the Neuber rule has been proposed to estimate elasto-plastic stresses and strains at notches. Predicted notch root stresses and strains from the proposed model are compared with non-linear Finite Element Analysis (FEA) results for SAE 1045 and SAE 1070 steel notched-bars. The SAE 1045 and SAE 1070 steel notch-bars are subjected to monotonic and cyclic non-proportional loadings respectively. The model shows very good agreements with the FEA data for both steel materials. [ABSTRACT FROM AUTHOR]

Additive manufacturing is revolutionizing processing in many applications including 3-D food printing. So far the number of suitable printable materials for food is limited and the microstructure and texture properties of 3-D printed food have been characterized poorly. This study introduces the novel concept of customizable water-based porous food simulants by 3-D printing using low methoxylated pectin gel as food-ink. A series of pectin gels was successfully 3-D printed by changing the formulation parameters including stirring rate and pectin, CaCl 2 , bovine serum albumin and sugar syrup concentrations. It was shown that food objects with variable microstructure and texture properties can be 3-D printed by using different pectin based food-inks. The pectin concentration was the main determinant of firmness and strength of the printed object. Sugar and pectin concentrations increased viscosity and affected the build quality. BSA stabilized and promoted the aeration of the food-ink. This resulted in a pore size distribution after printing that was influenced by the viscosity of the food-ink. A predictive model was established for designing the food-ink composition to obtain 3-D printed food simulants with a priori defined microstructure and texture. [ABSTRACT FROM AUTHOR]

The precise role of the acromioclavicular and coracoclavicular ligaments during shoulder motion is unclear. We evaluate changes in the stress-strain distribution of the acromioclavicular joint's ligaments during different shoulder passive motion positions. A 3D acromioclavicular joint model was reconstructed. A constitutive hyperelastic model was used for the ligaments. The kinematics of the shoulder girdle was taken to simulate shoulder abduction (Motion 1) and horizontal adduction (Motion 2). A computer-generated quasi-static and non-linear finite element model was used to predict the 3D stress-strain distribution pattern of the acromioclavicular ligament and the coracoclavicular ligament complex. In motion 1, from 20 to 90° the peak von Mises stress was found in the conoid (4.14 MPa) and the anteroinferior bundle (2.46 MPa), while from 90 to 120° it was found in the conoid and the trapezoid. However, there were no significant differences between the mean stress values between anteroinferior bundle and trapezoid throughout the motion (p = 0.98). In Motion 2, from 20 to 80° the maximum equivalent elastic strain was found in the anteroinferior bundle (0.68 mm/mm) and the conoid (0.57 mm/mm), while from 80 to 100° it was higher in the conoid (0.88 mm/mm) than in the anteroinferior bundle (0.77 mm/mm). The coracoclavicular ligament complex demonstrated a high stress-strain concentration during simulated passive shoulder abduction. Additionally, it was shown that the acromioclavicular ligament plays an important role in joint restraint during passive horizontal adduction, changing the primary role with the trapezoid and conoid at different motion intervals. • The conoid ligament is the primary stabilizer in shoulder abduction. • Anteroinferior bundle is a secondary restrictor up to 90° of shoulder abduction. • Trapezoid is primary stabilizer up to 80° of shoulder horizontal adduction. • The anteroinferior bundle and coracoclavicular ligaments switch roles in adduction. • Superoposterior bundle has a minor stabilizer role in both motions. [ABSTRACT FROM AUTHOR]

This study aimed to analyze experimentally and by modeling the shrinkage deformation of Japanese eggplant ( Solanum melongena ) during roasting by simultaneous heat and moisture transport model coupled with a structural mechanics model applicable to a body undergoing volumetric changes, as a consequence of moisture removal. Cylindrical slices (45 mm × 10 mm) were roasted for up to 15 min. Roasting experiments were performed using a convection-oven at 250 °C. Several coefficients and parameters required for calculations were experimentally obtained. An implicit finite element method was applied using a FORTRAN program. In this study, an approximately equal reduction rate in moisture content losses and volume shrinkage was observed ( R 2 ≥ 0.99). The volumetric ( S v ) and directional shrinkage were successfully estimated by developed empirical equations (e.g. R 2 > 0.98 for S v ). The simulation of temperature and moisture distribution undergoing shrinkage deformation confirmed the importance of internal evaporation in the transport model. [ABSTRACT FROM AUTHOR]

Most of the notched components for ground vehicles experience complex multiaxial loadings, where principal stresses rotate and change non-proportionally their magnitudes during a loading cycle. Furthermore, many vehicle components contain notches and geometrical irregularities because of design requirements. These geometric discontinuities cause significant stress concentrations. Multiaxial loads result in complex stress and strain responses at notch areas and can induce a fatigue failure even without any warning of noticeable plastic deformation. Unfortunately, the combination of multiaxial loading paths and complex geometries of mechanical components is unavoidable in practice and experiments performing durability test for ground vehicles are often not feasible because of time and cost considerations. Therefore, an innovative computational fatigue analysis methodology has been proposed here for multiaxial fatigue life analysis of notched components under design process using analytical and numerical methods. The proposed multiaxial fatigue analysis methodology consists of an elastic–plastic stress–strain model and a multiaxial fatigue damage parameter. Computed results of the proposed methodology are compared to sets of experimental published data to verify the prediction capability of the elastic–plastic stress–strain model and the fatigue damage parameter. A comparison of analysis results and experimental data shows that the multiaxial elastic–plastic stress–strain model correlates well with experimental strain data for SAE 1070 steel notched bars subjected to complex non-proportional load paths. The proposed fatigue damage parameter correlates well with fatigue data of 1045 steel and Inconel 718 tubular specimens under proportional and non-proportional loadings. Finally the complete analysis methodology incorporating both the elastic–plastic stress–strain model and the multiaxial fatigue damage parameter is found to be in a good agreement with experimental data of SAE 1045 steel notched shafts subjected to proportional and non-proportional loadings. [ABSTRACT FROM AUTHOR]

An elastoplastic semi-analytical method is proposed to deal with the plastic mechanical behavior of buried pipelines subjecting to landslides based on the plane stress condition, considering the inner pressure and the temperature variation. According to the incremental theory of plasticity, the longitudinal, radial and hoop plastic strains are expressed as the corresponding equations that contain the longitudinal and hoop stresses. Considering the effect of the inner pressure and the temperature variation, the longitudinal stress is derived based on the elastoplastic-beam theory, and then the axial force can be determined based on the relation of the internal force and the stress. Combining the differential equation and the boundary condition, the transverse horizontal displacement, the bending strain, axial strain can be obtained. To verify the proposed model, the comparison of the obtained results from the proposed method and the finite element method is performed, with minor deviations of within 5.4%. Additionally, the effects of the inner pressure and the temperature variation on the strain and displacement of pipelines are investigated through parametric studies. The results show that the plastic deformation and strain are much larger when neglecting operating loads; the pipeline develops mainly the longitudinal and radial plastic deformations instead of the hoop plastic deformation. [ABSTRACT FROM AUTHOR]

High-temperature deformation behaviors of a nonequiatomic novel AlNbTi 3 VZr 1.5 refractory high entropy alloy were studied. Hot compression tests were carried out at different temperatures ranging from 1100 to 1250 ℃ and various strain rates from 0.001 to 1 s−1. The true stress-true strain curves indicated obvious sharp drops in the flow stress after reaching peak stress. This may be caused by either dislocation unlocking from a substitutional solute atmosphere or destroying short-range ordered structures. Flow stress analysis was investigated by introducing the Arrhenius constitutive relation. The apparent activation energy (Q) for high-temperature deformation was calculated to be 228.1 kJ/mol. The processing maps show that the best processing window was determined at 1200–1250 °C and 10−0.75 to 1 s−1. Detailed microstructure evolution characterization with EBSD analysis shows that the occurrence of discontinuous dynamic recrystallization along grain boundaries is the main softening mechanism of the AlNbTi 3 VZr 1.5 RHEA during the hot compression deformation. The size and volume percentage of dynamically recrystallized grains increase as the Z parameter decreases. • The high-temperature behavior of novel AlNbTi 3 VZr 1.5 refractory high entropy alloy is investigated. • The apparent activation energy was 228.1 kJ/mol. • The best processing window is determined at 1200–1250 °C and 10–0.75–1 s−1. • Discontinuous dynamic recrystallization along grain boundaries is the main softening mechanism of the AlNbTi 3 VZr 1.5 RHEA during the hot compression deformation. [ABSTRACT FROM AUTHOR]

Abstract: Based on the Duncan-Chang hyperbolic nonlinear elastic material model, this paper carried out the stress and strain numerical analysis of a clay core rock-fill dam, which is a certain building reservoir dam in Yunnan province. By loading on each layer step by step and with the static nonlinear finite element simulation of deposition, it obtained the results of the stress and deformation of the clay core rock-fill dam. The calculation showed that the great difference in deformation modulus causes non-smooth variations in deformation, stress and strain between the transition area and the rock-debris fill. From the analysis it can be seen that the present design of the dam is reasonable since no any abnormal stresses and deformations occurred in the dam. Moreover, this also indicated a feasible and provided a valuable evident for the optimization of cross-section zones in a project. [Copyright &y& Elsevier]

Abstract: The paper deals with a new structural system of pedestrian steel bridge consisting of carrying suspension members made of stiff (in bending) rolled or welded sections and a flexible cylindrical deck. Structural behaviour of such a suspension member subjected to unsymmetrical live loading has been discussed on a basis of kinematic conditions. Ways of stabilization of kinematic displacements have been under consideration. Effects of bending stiffness and geometrical non-linearity of the suspension structure are taken into account. Analytical expressions for the analysis of the flexible cylindrical deck have been proposed. In an alternative concrete deck, a layered model has been applied for the stress and strain analysis. [Copyright &y& Elsevier]

Abstract: A finite element model, using commercially available software, is presented to simulate the piezoelectrically induced stresses and strains in an optical fibre to be used as antenna. These stresses and strains are generated by a layer of piezoelectric polymer deposited on the cladding of a short fibre sample. The theoretical basis for the work is briefly explained and the modelling process is emphasised. Two types of fibre are investigated – circular fibre and D-fibre, and the results compared, analysed and discussed. It is shown that in the D-fibre, the stress and displacement increased by 1.46 and 115 times, respectively, in comparison with the circular fibre. [Copyright &y& Elsevier]

A method for the estimation of time-dependent strains and stresses induced in notches has been developed. The aim of the method is to generate a solution for the creep strain and stress at the notch root based on the linear-elastic stress state, the constitutive law, and the material creep model. The proposed solution is an extension of Neuber’s total strain energy density rule for the case of time-independent deformation. The method was derived for both localized and non-localized creep in a notched body. Predictions were compared with finite element data and good agreement was obtained for various geometrical and material configurations in plane stress conditions. [Copyright &y& Elsevier]

The passive elastic characteristics of the abdominal aorta were investigated in two experimental animal models, aiming at assessing the stress–strain relation of the aortic wall. Twenty porcine and 15 rabbit healthy abdominal aortas were subjected to uniaxial stress–strain analysis, performed on a tensile-testing device, while immersed in a physiologic saline bath at body temperature. Measured parameters included original length, width and thickness, as well as axial force and extension. Based on these data, Kirchhoff stress and Green–St.Venant strain were computed and one-dimensional constitutive equations were defined, comprising of a power function and two exponential ones, in turn, for the low, physiologic and high-stress regions. The stress–strain curves were plotted as elastic modulus versus stress, displaying nonlinear part I and linear parts II and III. These were regressed, yielding parameters k, q (part I), a, b (part II) and c, d (part III). A detailed comparison of these constitutive parameters was undertaken between the two species, demonstrating variations in d (p<0.05). No statistical differences were found in parameters a, b, c, k and q, implying that the two aortas were equally stiff under low and physiologic stresses, whereas the porcine aorta was stiffer at higher stresses. In conclusion, a bi-exponential in addition to a power law was established, relating stress and strain in the aorta, which is advantageous in comparison with previous constitutive equations. Under passive conditions, the nonlinear nature of this constitutive law may account for the low, part I, physiologic, part II, and high-stress, part III of the stress–strain relationship, supporting the concept of the aortic wall as a biphasic material. [Copyright &y& Elsevier]

This research involves an application of reflection photoelasticity used to analyze stressed samples. The poly(methyl methacrylate) (PMMA) had a rectangular shape 2.5 × 2.5 × 0.6 cm and was compressed by hydraulic press system. The observation of a stressed sample using reflection photoelasticity showed isochromatic and isoclinic fringe patterns. We adjusted the polariscope to determine the photoelastic parameters, namely fringe order, angle principal stress and strain value, which were used to calculate the stress-strain based on calibration, shear difference method and stress-strain optic law. It was found that maximum normal stress (y-direction) and strain values were at contact area and decreased to the edge and center along horizontal and vertical direction of sample. Shear stress depended on multiple of fringe order and sin 2 θ. It was zero along center of vertical and horizontal direction of sample. [ABSTRACT FROM AUTHOR]

Although cardiac wall mechanics is of importance for understanding heart failure with preserved ejection fraction (HFpEF), there is a lack of relevant mechanics studies. The aim of this study was to analyze the changes in stress and strain in the left ventricle (LV) in hypertension-induced HFpEF rats. Based on experimental measurements in DSS rats fed with high-salt (HS) and low-salt (LS) diets, LV stress and strain were computed throughout the cardiac cycle using Continuity software. HS-feeding increased myofiber stress and strain along both the transmural and longitudinal directions at the end-diastolic state but resulted in a lower absolute value of strain and relatively unchanged stress at the end-systolic state. Moreover, the end-diastolic stress and strain decreased with increasing radial position from the endocardial towards the epicardial walls despite negligible changes along the longitudinal direction. The changes in LV wall mechanics characterized the elevated diastolic LV stiffness and slow LV relaxation in HS-fed rats of HFpEF. These findings denote that a vicious cycle of increased stress and strain and diastolic dysfunction can prompt the development of HFpEF. [ABSTRACT FROM AUTHOR]