Influence Of Residual Thermal Stresses Research Articles

Thermal and Mechanical Analysis of Bimodular Beam

"The paper demonstrates the analysis of cantilever beam having dissimilar modularity in tensile and compressive tests liable with thermal and mechanical loading. The prime objective is to evaluate the governing differential equations to determine the displacements of the bimodular beam under combined loading of force and temperature. Also, the impact of ply lay-up and influence of residual thermal stresses and elastic loading on the cantilever bimodulus beam has been computed. Stress and flux analyses of beam made up of laminated Fiber Reinforced Polymeric (FRP) composite are computed with the help of Finite Element Analysis. The results show that the stresses and flux is increases with the advancement in bond length.

Numerical Study of the Influence of Residual Thermal Stresses on the Fracture of Metal Matrix Composites

A numerical study of the mechanical behavior of the «aluminum-boron carbide» composite material under different thermomechanical loading is performed. The complex structure of the composites is explicitly taken into account in the calculations. Isotropic elastoplastic and elastic-brittle constitutive models are used to describe the mechanical response of the aluminum matrix and ceramic particles, respectively. Huber type fracture criterion taking into account the local stress state: bulk tension, or compression, is chosen to study the origination and propagation of cracks in ceramic particles. The composite material microvolume with a single boron carbide particle embedded into the aluminum matrix is considered. The influence of the residual thermal stresses arising during cooling of the composite material from temperature close to the temperature of recrystallization of aluminum to the room temperature on the ceramic particle fracture is investigated. Dynamic boundary value problems are solved numerically by the finite element method in the ABAQUS / Explicit software package.

Influence of residual thermal stresses on the edge chipping resistance of PFM and veneered zirconia structures: Experimental and FEA study

ObjectiveChipping fractures of the veneering porcelain are frequently reported for veneered all-ceramic crowns. In the present study, the edge chipping test is used to measure the toughness and the edge chipping resistance of veneered zirconia and porcelain-fused-to-metal (PFM). The aim is to describe an edge chipping method developed with the use of a universal testing machine and to verify the accuracy of this method to determine the influence of residual thermal stresses on the chipping fracture resistance of veneering porcelain. A finite element analysis (FEA) was used to study the residual stress profiles within the veneering porcelain. MethodsVeneered zirconia and PFM bar specimens were subjected to either a fast or a slow cooling protocol. The chipping resistances were measured using the edge chipping method. The load was applied in two different directions, in which the Vickers indenter was placed in the veneering porcelain either parallel or perpendicular to the veneer/framework interface. The mean edge chipping resistance (ReA) and fracture toughness (KC) values were analysed. ReA was calculated by dividing the critical force to cause the chip by the edge distance. KC was given by a fracture analysis that correlates the critical chipping load (FC) regarding edge distance (d) and material toughness via KC=FC/(βd1.5). ResultsThe ReA revealed similar values (p>0.005) of chipping resistance for loads applied in the parallel direction regardless of framework material and cooling protocol. For loads applied in the perpendicular direction to the veneer/framework interface, the most chip resistant materials were slow cooled veneered zirconia (251.0N/mm) and the PFM fast cooled (190.1N/mm). KC values are similar to that for monolithic porcelain (0.9MPa.√m), with slightly higher values (1.2MPa.√m) for thermally stressed PFM fast cooled and veneered zirconia slow cooled groups. SignificanceThe developed and reported edge chipping method allows for the precise alignment of the indenter in any predetermined distance from the edge. The edge chipping method could be useful in determining the different states of residual thermal stresses on the veneering porcelain.

Influence of residual thermal stresses on fatigue crack growth life of discontinuous reinforcements in metal matrix composites

AbstractThe fatigue life prediction model based on crack propagation from micro‐structural features is derived and presented for planar and randomly oriented Discontinuous Reinforced Metal Matrix Composites (DRMMCs). The model contains the influence of micro‐structural properties such as aspect ratio, volume fraction of particle/fibre and constraint between particle and the matrix. The effect of residual thermal stresses generated within the matrix during development of composite is considered. The particle/fibre plays a dominant role in the development of the cyclic plastic zone size ahead of the crack tip; moreover, it enhances the cyclic plastic deformation characteristics of DRMMC. The theoretical model‐based evaluations for low cycle fatigue in DRMMCs are within the proximity of the experimental results.

The influence of residual thermal stresses on the mechanical properties of multilayer α-Al2O3/TiCxN1 − x coatings on WC/Co cutting tools

Orientation maps of the microstructures of four α-Al2O3 and TiCxN1−x multilayer coatings on WC–Co cemented carbide tool bit inserts were used to create realistic models for finite element calculations of residual thermal stresses. The calculations show that channel cracks in the coatings relieve thermal stresses and that the amount of stress relieved increases with film thickness. The hardness and fracture toughness of the coatings, measured by nano-indentation, are inversely correlated to the calculated mean thermal stress, where the hardest sample has the smallest calculated mean thermal stress. The calculations also indicate that cracks spaced more closely than about 50μm are not effective in further reducing residual stresses.

Carbon fibre pullout under the influence of residual thermal stresses in polymer matrix composites

► The anisotropic property of carbon fibres has significant effect on thermal residual stresses. ► The residual thermal stress has a significant influence at frictional sliding stage of fibre pullout. ► The interfacial shear strength is not a constant and decreases with the fibre embedded length. ► The specific pullout energy increases with the embedded length. ► The specific pullout energy does not depend on the fibre radius. A single carbon fibre pullout from a polymer matrix under the influence of residual thermal stresses was numerically investigated in this paper. The finite element method was first applied to obtain the residual thermal stress components along the interface between the fibre and the matrix due to curing. Four typical carbon fibres, T300, AS4, T800HB-40B and IM7 with anisotropic properties embedded in epoxy matrix HY6010 were considered. A comparison study indicates that simplified isotropic fibre model would overestimate the compressive residual axial and interfacial radial stress by up to 30%. Therefore, the anisotropic material properties of the fibres should be considered in the theoretical study of carbon fibre pullout. The cohesive zone model was then used to study the single carbon fibre pullout test. The numerical results indicate that the residual thermal stresses have a significant influence on fibre pullout at the stage of frictional sliding after interfacial debonding, which leads higher specific pullout energy. The effects of interfacial bonding condition and the fibre geometry were investigated by a parametric study. An interesting finding is that the interfacial shear strength, which is defined as the ratio of the debonding force to the embedded area, is not a constant. It decreases with the increase in the fibre embedded length. In addition, the fibre pullout energy per unit interfacial area (specific pullout energy) increases with the embedded length due to the effect of residual thermal stresses and interfacial friction. But the specific pullout energy does not depend on the fibre radius, which means that reducing fibre radius alone would not enhance the fibre bridging effect.

Cryogenic mechanical response of multilayer satin weave CFRP composites with cracks

We deal with the thermomechanical response of multilayer satin weave carbon-fiber-reinforced polymer (CFRP) laminates with internal and/or edge cracks and temperature-dependent material properties subjected to tensile loading at cryogenic temperatures. The composite material is assumed to be under the generalized plane strain. Cracks are located in the transverse fiber bundles and extend to the interfaces between two fiber bundles. A finite-element model is employed to study the influence of residual thermal stresses on the mechanical behavior of multilayer CFRP woven laminates with cracks. Numerical calculations are carried out, and Young’s modulus and stress distributions near the crack tip are shown graphically.

Influence of residual thermal stresses and geometric parameters on stress and electric fields in multilayer ceramic capacitors under electric bias

The stress and electric fields in multilayer ceramic capacitors (MLCCs) under an applied electric bias were investigated by using a three-dimensional finite element model of ferroelectric ceramics. A coupled thermal–mechanical analysis was first made to calculate the residual thermal stress induced by the sintering process, and then a coupled electrical–mechanical analysis was performed to predict the total stress distribution in the MLCCs under a representative applied electric bias. The effects of the number of dielectric layers, the single layer thickness as well as the residual thermal stresses on the total stresses were all examined. The numerical results show that the residual thermal stress induced by the sintering process has a significant influence on the contribution of the total stresses and, therefore, should be taken into account in the design and evaluation of MLCC devices.

Thermoelastic analysis of the asymmetries of interfacial embedded delamination characteristics in laminated FRP composites

This paper presents two sets of full three-dimensional thermoelastic finite element analyses of superimposed thermo-mechanically loaded FRP composite laminates with embedded interfacial elliptical delaminations, emphasizing the influence of residual thermal stresses and material anisotropy on the delamination fracture behavior characteristics. Modified crack closure integral (MCCI) methods based on the concepts of linear elastic fracture mechanics (LEFM) have been used as a meaningful tool to calculate the individual modes of strain energy release rates from the thermoelastic stress and displacement fields due to a combined thermal and a quasi-static impact loading. Residual stresses developed due to the thermoelastic anisotropy of the laminae are found to strongly influence the delamination onset and propagation characteristics, which have been reflected by the asymmetries in the nature of energy release rate plots and their significant variation along the delamination front.

514 き裂を有する二層平織ガラス繊維強化プラスチック積層材料の極低温応力拡大係数に及ぼす残留熱応力の影響

514 き裂を有する二層平織ガラス繊維強化プラスチック積層材料の極低温応力拡大係数に及ぼす残留熱応力の影響

Thermoelastic analysis of cracked woven GFRP laminates at cryogenic temperatures

We deal with the thermal–mechanical response of multi-layered G-11 woven glass/epoxy laminates with cracks and temperature-dependent properties under tension at liquid helium temperature (4 K). The composite material is assumed to be in generalized plane strain. Cracks are located in the fill fiber bundles and are assumed to span the width of the fill fiber bundles. Finite element model is used to study the influence of residual thermal stresses on the mechanical behavior of multi-layered woven laminates with cracks. Numerical calculations are carried out, and the Young's modulus and stress distributions near the crack tip are shown graphically.

513 き裂を有する極低温用平織 GFRP 積層板の熱弾性解析

Abstract We deal with the thermal–mechanical response of multi-layered G-11 woven glass/epoxy laminates with cracks and temperature-dependent properties under tension at liquid helium temperature (4 K). The composite material is assumed to be in generalized plane strain. Cracks are located in the fill fiber bundles and are assumed to span the width of the fill fiber bundles. Finite element model is used to study the influence of residual thermal stresses on the mechanical behavior of multi-layered woven laminates with cracks. Numerical calculations are carried out, and the Young's modulus and stress distributions near the crack tip are shown graphically.

Mechanical behaviour of cracked woven glass/epoxy laminates under tension at low temperatures

We considered the thermomechanical response of cracked G-10CR glass/epoxy laminates with temperature-dependent properties. A finite element method was used to study the influence of residual thermal stresses and warp angles on the mechanical behaviour of a two-layer woven laminate with a fill crack at low temperatures. Numerical calculations were carried out, and the mechanical properties and stress distributions at low temperatures are shown graphically for various warp angles. The stiffness was found to increase with decreasing values of temperature Φ and warp angle θ. The influence of the crack on the stiffness was also examined. The existence of a crack produced lower stiffness, and the tendency was more pronounced with increasing warp angles. The lower temperature produced a higher tensile-stress concentration in the crack-tip area, and the debonding stress tended to increase with increasing θ and decreasing Φ.

Influence of Residual Thermal Stresses on the Fracture Behavior of Hybrid Bonded Joints

Abstract The objective of this work is to study the influence of the residual thermal stresses on the fracture behavior of hybrid composite-aluminium bonded joints. A modified DCLS specimen is designed and the strain energy release rate is determined using both an analytical fracture mechanics based method and a finite element method. The residual thermal stresses, which appear in the adhesive because of the difference between the curing and the service temperatures, are evaluated with a two-ply laminate specimen. Some rupture tests are performed on the DCLS specimens at different temperatures and for different geometries and materials. The results show a good agreement between analytical calculations, numerical analysis and experiments. The residual thermal stresses are never negligible in the considered hybrid bonded joints and do influence their fracture behaviors. Although the designed specimen is not adapted to study fatigue crack propagation, it provides a simple way to study the crack initiation an...