Different Properties In Tension Research Articles

Numerical modeling of the mechanical response of asphalt concrete in tension and compression

Asphalt concrete (AC) shows significant tension-compression (TC) asymmetry, i.e., different properties in tension and compression (T&C). This asymmetry may profoundly affect AC's performance and deterioration in the field, but limited studies have been performed to quantify this behavior. This study aims to quantitively characterize the global and local mechanical responses of AC in T&C through numerical modeling. To this end, three AC mixtures: the gap-graded SMA10, dense-graded AC20, and open-graded mixtures PA13, were evaluated experimentally and numerically. Digital image processing was used to generate image-based AC models with contact regions (CR), and dynamic simulations were conducted using the steady-state dynamics (SSD) approach. The results indicated that the measured and predicted master curves for AC in T&C qualitatively agree and demonstrate significant asymmetry, with higher moduli but lower phase angles in compression compared to tension. Among the mixtures, PA13 exhibited the most pronounced asymmetry, followed by SMA10 and AC20. Statistical analyses of local stress and strain found that the stress and strain in different phases show significant variations, with more pronounced disparities observed at lower frequencies. Notably, at 10−6 Hz for PA13 in compression, the stress within the aggregate phase exceeded that of the matrix phase by over 250 times, while the strain within the matrix phase surpassed the aggregate phase by more than 600 times. To enhance pavement durability, it is recommended to consider AC's TC asymmetry in pavement design.

Identification of temperature-dependent parameters for an elastic–plastic-damage material model of 3D-printed PETG

The presented paper focuses on identifying temperature-dependent parameters for a newly designed material model of 3D-printed PETG (polyethylene terephthalate glycol). An uniaxial elastic–plastic material model with damage and different properties in tension and compression was developed to describe this material’s non-linear behaviour. The monotonic and cyclic tests were carried out in tension and compression at several temperatures. The specimens were printed using FDM (fused deposition modelling) technology on the printer from Prusa Research. The principal material parameters such as Young’s modulus, yield stress and ultimate tensile stress were derived directly from the force–displacement diagrams obtained experimentally. Other necessary material characteristics were identified using numerical simulations combining the finite element method and parametric optimization. The model was implemented for the software Abaqus using subroutine UMAT and the optimization was performed using software Isight.

Solution of the Thermoelastic Problem for a Two-Dimensional Curved Beam with Bimodular Effects

In classical thermoelasticity, the bimodular effect of materials is rarely considered. However, all materials will present, in essence, different properties in tension and compression, more or less. The bimodular effect is generally ignored only for simple analysis. In this study, we theoretically analyze a two-dimensional curved beam with a bimodular effect and under mechanical and thermal loads. We first establish a simplified model on a subarea in tension and compression. On the basis of this model, we adopt the Duhamel similarity theorem to change the initial thermoelastic problem as an elasticity problem without the thermal effect. The superposition of the special solution and supplement solution of the Lamé displacement equation enables us to satisfy the boundary conditions and stress continuity conditions of the bimodular curved beam, thus obtaining a two-dimensional thermoelastic solution. The results indicate that the solution obtained can reduce to bimodular curved beam problems without thermal loads and to the classical Golovin solution. In addition, the bimodular effect on thermal stresses is discussed under linear and non-linear temperature rise modes. Specially, when the compressive modulus is far greater than the tensile modulus, a large compressive stress will occur at the inner edge of the curved beam, which should be paid with more attention in the design of the curved beams in a thermal environment.

A complemented multiaxial creep constitutive model for materials with different properties in tension and compression

A complemented multiaxial creep constitutive model is proposed in this paper. The model is able to describe the different creep behaviors in tension and compression under a complex multiaxial stress state. To improve the convergence and adaptability for large-scale structures in engineering, a complemented constitutive model is established by complementing the shear part of the creep constitutive matrixes in principal space through a limitation process. The finite element method and forward Euler method are used to establish the numerical calculation framework. Efficient solution procedures are also proposed and implemented. Room temperature creep experiments of titanium alloy Ti–6Al–3Nb–2Zr–1Mo are performed. It is found that titanium alloy has different creep properties in tension and compression. The numerical results show that the proposed creep constitutive model and numerical calculation framework are in good agreement with the experimental results. The response of each specific creep strain component under a complex stress multiaxial state can be accurately calculated, and the different properties of the creep response in tension and compression in different directions are reflected.

Evolutionary topology optimization for structures made of multiple materials with different properties in tension and compression

Structural optimization techniques for single-material continuum have been well developed and widely applied. However, topology optimization techniques with multiple materials, especially those with distinctly different mechanical properties in tension and compression, require significant improvement. Built on the bi-directional evolutionary structural optimization (BESO) technique for a single material, this paper proposes a method which takes material utilization as the criterion for determining the importance of the materials to the whole structure and assigns a suitable material for each element according to the sum of the principal stresses to obtain an efficient multi-material distribution. Numerical examples are presented to demonstrate the effectiveness of the proposed method in material saving and safety enhancement. The application of the method to the topology optimization of bridges with different support conditions and multi-span continuous bridges shows that the new technique has significant practical value for the conceptual design of multi-material structures.

Structural model for rigid-plastic yielding behavior of angle-ply reinforced composites of materials with different properties in tension and compression considering 2D stress state in all components

Structural model for hybrid media, angle-ply reinforced in the plane allowing one to determine the yield loci for the composition considering the plane stress state in all components is constructed. The materials of the composition are homogeneous, isotropic and have different yield strengths in tension and compression. Their mechanical behavior is described by the associated flow rule for rigid-plastic bodies with the quadratic yield conditions. The yield loci for metal compositions with low-strength and high-strength binder and for glass-plastic composition are calculated.

Construction of Constitutive Equations for Orthotropic Materials with Different Properties in Tension and Compression under Creep Conditions

Constitutive steady-state creep equations are proposed for orthotropic materials with different tensile and compressive resistances. The resistances are described using lower functions with different exponents for tension and compression. Equations are written for tension, shear, and plane stress problems. The model is used to solve the problem of torsion by a constant moment at a temperature T = 200°C for annular cross-section rods cut from a plate of AK4-1 transversely isotropic alloy in the normal direction to the plate and in the longitudinal direction. Constitutive equations for torsion are derived. Values of model parameters were obtained in experiments on uniaxial tension and compression of solid circular specimens cut in various directions. An analytical solution for the rate of torsion angle of a circular cross-section rod cut normal to the plate was obtained for the same exponent in tension and compression. For a rod cut in the longitudinal direction, an upper estimate of the torsion angle rate was obtained. The calculated results are in satisfactory agreement with experimental data.

One-Dimensional Theoretical Solution and Two-Dimensional Numerical Simulation for Functionally-Graded Piezoelectric Cantilever Beams with Different Properties in Tension and Compression.

The existing studies indicate polymers will present obviously different properties in tension and compression (bimodular effect) which is generally ignored because of the complexity of the analysis. In this study, a functionally graded piezoelectric cantilever beam with bimodular effect was investigated via analytical and numerical methods, respectively, in which a one-dimensional theoretical solution was derived by neglecting some unimportant factors and a two-dimensional numerical simulation was performed based on the model of tension-compression subarea. A full comparison was made to show the rationality of one-dimensional theoretical solution and two-dimensional numerical simulation. The result indicates that the layered model of tension-compression subarea also makes it possible to use numerical technique to simulate the problem of functionally graded piezoelectric cantilever beam with bimodular effect. Besides, the modulus of elasticity E* and the bending stiffness D* proposed in the one-dimensional problem may succinctly describe the piezoelectric effect on the classical mechanical problem without electromechanical coupling, which shows the advantages of one-dimensional solution in engineering applications, especially in the analysis and design of energy harvesting/sensing/actuating devices made of piezoelectric polymers whose bimodular effect is relatively obvious.

Deformation of T-shaped beams under creep conditions with different properties in tension and compression

An algorithm is implemented to simulate a pure bending of a beam of a symmetric section under creep conditions. The beam is subjected to a bending moment with a constant absolute value. The algorithm is applied to the experimental data on the pure bending of T-beams made from a Ti-Al-Sn-V alloy at a temperature T = 700°C. The algorithm takes into account the accumulation of damage in the material, the effect of temperature exposure and the difference properties of the material under tension and compression. The model is based on kinetic creep theory by Rabotnov. The Nelder-Mead procedure is used to find the bending moment by the curvature of a beam.

Bending analysis of functionally graded curved beams with different properties in tension and compression

In this study, we obtained analytical solutions for functionally graded curved beams with different properties in tension and compression, in which the moduli of elasticity in tension and compression are assumed as two different exponential functions. First, by determining the unknown neutral layer, we established a simplified mechanical model concerning tension and compression subzone and derived the one-dimensional solution (i.e., the solution in the scope of mechanics of materials). Given that the one-dimensional solution is a relatively simplified one, thus a comprehensive understanding of this problem is still needed. For this purpose, we established the consistency equation expressed in terms of stress function under two-dimensional theory of elasticity. Combining boundary conditions of inner and outer edges with continuity conditions of the neutral layer, we applied power series method for the solution of stress components under pure bending. The variations of radial and circumferential stresses in different cases of bimodular functionally graded parameters are comprehensively analyzed with numerical examples. Results indicate that the position of the neutral layer is generally related to the elastic modulus and the functionally graded coefficients of the materials. Moreover, the maximum tensile or compressive bending stress may not take place at the outer or inner edges of the curved beam but inside the beam, which should be given more attention in the analysis and design of functionally graded curved beams with different properties in tension and compression.

Non-Linear Bending of Functionally Graded Thin Plates with Different Moduli in Tension and Compression and Its General Perturbation Solution

In this study, a set of Föppl–von Kármán equations for a bimodular functionally graded thin plate subjected to a uniformly distributed load is established, and its general perturbation solution in axisymmetric case is also obtained under different boundary conditions. First, the equation of equilibrium of the plate is established on the existence of the neutral layer when considering different properties in tension and compression. During the derivation of the consistency equation, the tensile effect in the thin plate with bimodular effect is fully taken into account. The perturbation method is used to solve the set of governing equations under different edge constraints, in which the central deflection and the load of the plate are taken as a perturbation parameter, respectively. The results indicate that the two selections for perturbation parameters are valid and consistent, and the two solutions are convenient for engineering application. This study also shows that the bimodular effect will modify the relation of load versus central deflection of the plate to some extent, and under the same edge constraint, the capacities resisting deformation in different cases of moduli depend on the relative magnitudes among the tensile modulus, the neutral layer modulus, and the compressive modulus.

Stress State Analysis of Iosipescu Shear Specimens for Aerogel Composite with Different Properties in Tension and Compression

The objective of present research is to establish guidelines for preparing shear tests of ceramic-fiber-reinforced aerogel. The aerogel composite prepared by Sol-gel methods exhibits bi-modulus properties under tension and compression loadings. Bi- modulus constitutive model of the aerogel composite was built, and then verified by analysis of bending test. Finite element analysis (FEA) was presented on Iosipescu specimens with different V-notch and Round-notch configurations. Several trends have become evident: stress state of bi-modulus aerogel is different from that of isotropic material; stress concentration is a strong function of V-notch tip radius, and increasing V-notch tip radius can effectively reduce normal stress concentration at notch tips; shear stress distribution in the test region can be modified by varying notch angle when V-notch tip radius≤1.3mm; increasing the Round-notch radius can also effectively reduce the normal stress concentration at notch tips. Based on these observations, Round-notch specimen seems to be a favorable choice for reducing the normal stress concentration at notch tips, especially the longitudinal tensile stress concentration. Round-notch specimen with r=4mm is favorable for the uniformly distributed shear stress in the test region. Digital image correlation (DIC) was suggested for shear strain measuring.

Modeling and short circuit detection of 18650 Li-ion cells under mechanical abuse conditions

In this research a simple, yet accurate model of a single cell, needed for safety assessment of batteries under mechanical abuse conditions, was developed. Extensive testing was performed on a 18650 lithium ion cell, including indentation by a hemispherical punch, lateral indentation by a cylindrical rod, compression between two flat plates, and three-point bending. The batteries were tested in an environmental chamber at a 10% SOC. A finite element model was developed, composed of shell elements representing outside casing, and solid elements for the active material with a binder lumped together with the current collectors and the separator. The jelly roll is modeled as a homogenized and isotropic material. The homogenous model assumes different properties in tension and compression, but does not account for the effect of structural anisotropy caused by the layered nature of the jelly roll. Very good correlation was obtained between LS Dyna numerical simulation and test results in terms of load–displacement relations, deformed shape of the battery, and initiation and propagation of a crack in the shell casing. The FE model was also capable of predicting the onset of short circuit of the cell.

Analysis of creep deformation and creep damage in thin-walled branched shells from materials with different behavior in tension and compression

A constitutive model for describing the creep and creep damage in initially isotropic materials with different properties in tension and compression has been applied to the modeling of creep deformation and creep damage growth in thin-walled shells of revolution with the branched meridian. The approach of establishing the basic equations for axisymmetrically loaded branched shells under creep deformation and creep damage conditions has been introduced. To solve the initial/boundary-value problem, the fourth-order Runge–Kutta–Merson’s method of time integration with the combination of the numerically stable Godunov’s method of discrete orthogonalization is used. The solution of the boundary value problem for the branched shell at each time instant is reduced to integration of the series of systems of ordinary differential equations describing the deformation of each branch and the shell with basic meridian. Some numerical examples are considered, and the processes of creep deformation and creep damage growth in a shell with non-branched meridian as well as in a branched shell are analyzed. The influence of the tension–compression asymmetry on the stress–strain state and damage evolution in a shell with non-branched meridian as well as in a branched shell with time are discussed.

Theory of creep deformation with kinematic hardening for materials with different properties in tension and compression

A constitutive model for creep deformation that describes the loading-history-dependent behavior of initially isotropic materials with different properties in tension and compression under stress vector rotations limited by 50–60° is presented within a thermodynamic framework. In the proposed constitutive model a kinematic hardening rule is adopted. This model also introduces an effective equivalent stress in the creep potential that is based on the first and second invariants of the effective stress tensor, and on the joint invariant of the effective stress tensor and eigenvector associated with the maximum principal Cauchy stress. The formulation of the kinematic hardening rule is presented and discussed. All the material parameters in the model have been obtained from a series of proposed basic experiments with constant stresses. These model parameters are then used to predict the creep deformation of the aluminum alloy under multiaxial loading with constant stresses, and under non-proportional uniaxial and non-proportional multiaxial loadings for both isothermal and nonisothermal processes.

Thermodynamic modeling of creep damage in materials with different properties in tension and compression

A constitutive model is developed to describe the creep response of polycrystalline metals and alloys with different behavior in tension and compression. A second-order damage tensor is introduced in order to describe the creep damage under nonproportional loading in nonisothermal processes. The thermodynamic formulation of the creep equation and the damage evolution equation is used to study the creep behavior and creep damage in the initially isotropic materials. The determination of the material parameters in the proposed equations is demonstrated from a series of basic experiments outlined in this paper. The results generated from the model are compared with those obtained from experiments under uniaxial nonproportional and multiaxial nonproportional loading for both isothermal and nonisothermal processes.

Modeling of secondary creep behavior for anisotropic materials with different properties in tension and compression

Abstract A constitutive model is developed to describe the anisotropic secondary creep response of polycrystalline metals and alloys with different behavior in tension and compression. The equivalent stress in the general anisotropic potential contains the linear and quadratic joint invariants of the stress tensor, and the second order and fourth order material tensors. In describing the creep behavior of orthotropic materials for the special case of coincidence of the coordinate axes with the principal directions of anisotropy, a nine parameter expression for the equivalent stress is proposed with the corresponding constitutive equation of creep. The determination of the material parameters in the proposed creep equation is obtained from a series of basic experiments outlined in this work. The results generated from the model are compared with those from experiments under multiaxial loading for various metallic materials.

A creep damage model for initially isotropic materials with different properties in tension and compression

A continuum damage mechanics model for the dislocation creep response associated with the growth of parallel planar mesocracks in initially isotropic materials is presented. The model describes simultaneously different damage development in tension, compression and torsion, damage-induced anisotropy, as well as different creep properties in tension, compression and torsion. The proposed constitutive equation for creep and the damage growth equation contain joint invariants of the stress tensor and the second-order damage tensor. The determination of the material parameters required in the proposed equations, from a series of basic experiments, is shown. Theoretical predictions are compared with experimental data for a multiaxial stress state of various materials in the primary, secondary and tertiary creep state under proportional and non-proportional loading.

Mechanical behaviour of bimodulus laminated plates

A new analytical method for the prediction of the mechanical behaviour of laminates consisting of layers having different properties in tension and compression is proposed in this paper. As a case study, bending of simply supported, multilayered, unsymmetric, specially orthotropic laminates under various types of lateral loads is considered. The underlying bending theory used is a higher-order shear deformation theory. With the proposed method, laminates having more than two layers, not necessarily in an antisymmetric stacking sequence, can be analyzed. The validity of the new method is confirmed by comparing its results with the ones of other simpler theories. Finally, as an example, deflections, strains and stresses are calculated for a five-layer, unsymmetric, specially-orthotropic laminate.

Stress-strain state at the crack tip under conditions of steady creep in materials having different properties in tension and compression

1. We obtained a modified singular solution of the problem of fracture mechanics for a body with a normal dilatational crack in steady creep when the behavior of the material is described by a determining equation that takes the effect of the kind of state of stress into account. 2. We dealt with the simplest function of the effect of the angle of the kind of state of stress ψσ as a result, it was established that the numerical values of the reduced functions\(\tilde \sigma _{ij} m(\theta )\) and\(\mathop {\dot \varepsilon }\limits^ \sim _{ij} m(\theta )\) and also In, m depend solely on the one parameter m. An analysis of the generalized dependence in the form (4) showed that the general structure of the solution (1) does not undergo any changes either, and the corresponding reduced functions and In depend on the numerical values of the constants of Eq. (4) which are found for the actual material.