Influence Of Deformation Mode Research Articles

Geometrically nonlinear analysis of perforated rack columns under a compression load by means of Generalized Beam Theory

This paper presents a simplified methodology to take perforations in rack columns into account by means of a geometrically nonlinear Generalized Beam Theory (GBT) analysis. A new GBT formulation, which considers perforation effects through the addition of supplementary terms in the finite element internal force and tangent stiffness matrices during the member analysis, is developed and evaluated. The critical loads, ultimate elastic loads, equilibrium paths and displacement fields obtained by the GBT formulation with perforations are successfully compared using a shell finite element analysis for distortional and global dominant failure modes. Furthermore, the possibility to extend an equivalent thickness approach to handle rack columns perforations in a nonlinear buckling analysis is assessed. Finally, the influence of deformation modes and limitations of the presented GBT formulation are discussed.

Influence of Deformation Mode on Hot Deformation Behavior of CP Titanium

Abstract To obtain desired properties, the microstructure of metallic materials is tailored by subjecting them to different thermomechanical processing routes. In manufacturing industries, metallic materials are subjected to different hot deformation processes, viz, rolling, extrusion, and forging, during which materials undergo deformation under complex stress state. Therefore, it is important to understand the effect of deformation mode on microstructure evolution during hot deformation. In the present work, we report systematic studies performed on the influence of deformation mode on dynamic recrystallization behavior of titanium. Titanium specimens were deformed through uniaxial compression (UC) and plane strain compression (PSC) at temperatures of 1,023, 1,073, and 1,123 K, and at strain rates of 0.01–1 s−1 to an equivalent strain of 0.5. Hot deformation experiments were conducted in a Gleeble thermomechanical simulator in an argon atmosphere. The specimens were water quenched immediately after the deformation process to arrest microstructure. To understand the deformation behavior of hot deformed specimens, flow curve analysis was performed. The microstructural characterization was performed through electron backscattered diffraction technique. The dynamic recrystallization (DRX) fraction is temperature and strain rate dependent. Significant difference in DRX fraction between PSC and UC is observed at 1,123 K at a strain rate of 0.1 s−1 and 1 s−1. In both, PSC- and UC-deformed specimens, DRX grains formed preferentially along grain boundaries through grain boundary bulging mechanism.

The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. III. The Influence of Nanosized SiC Powder Content and Deformation Processing on the Properties of AMg5 Alloy Powder Composites

The structure and mechanical properties of a powder composite with an AMg5 alloy metallic matrix reinforced with SiC particles have been examined. The composite with 3% reinforcing phase shows the best combination of strength, ductility, and damping capacity. Additional deformation processing of the composite improves its strength but reduces ductility because of planar pores observed on the fracture surface of severely deformed samples. It is shown that 30% strain hardening in the rolling process is not accompanied by reduction in ductility.

The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. II. High-Alloyed Al–Mg Powder Materials

The influence of deformation modes on the structure and mechanical properties of powder materials produced from aluminum–magnesium alloys by ultrafast melt crystallization with high-pressure water atomization was studied. Extrusion of powder pellets onto a ribbon followed by its symmetric or asymmetric rolling was used as the deformation technique. The influence of the symmetric and asymmetric rolling modes on the mechanical properties of high-doped Al–11.2 Mg–2.2 Mn–0.6 Zr and Al–3 Mg–8 Fe–0.5 Zr powder materials was examined. It is shown that rolling significantly increases the strength of the resultant products, asymmetric rolling being more effective than symmetric one.

The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. I. The Influence of Rolling Conditions on the Mechanical Properties of Aluminum Powder Ribbons Strengthened with SiC Nanoparticles

The influence of deformation modes on the mechanical properties of metal matrix composites produced from the aluminum powder strengthened with SiC nanoparticles has been studied. Symmetric and asymmetric rolling processes were employed at room temperature. Rolling as an additional deformation processing step improves the composite structure by refining the SiC agglomerates, asymmetric rolling being a more effective deformation processing technique. This complex hardening mechanism allows the strength to be increased twofold without decrease in the elastic and ductile parameters.

Tensile and compressive deformation behavior of the Al–Si–Cu–Mg cast alloy with additions of Zr, V and Ti

The deformation behavior of the Al–Si–Cu–Mg cast alloy with micro-additions of Zr, V, and Ti was investigated under uniaxial tension and compression. It was found that after T6 heat treatment the change of the load from tension to compression caused an increase in strength from 348MPa to 417MPa and in fracture strain from 1.3% to 37.0%. As calculated based on Mott’s theory of strain hardening, the dislocation slip distance in compression was twice of that in tension. The observed differences in alloy fracture strain were explained by changes in re-orientation and fracturing of the eutectic silicon particles. Due to deformation, fracturing of the silicon particles occurred with major cracks being parallel to the compression axis but perpendicular to the tensile load axis. An influence of deformation mode on change in orientation of the silicon particles was revealed. While for tensile load, the silicon particles were stationary during deformation and exhibited an orientation practically the same as in unstrained structure, for compression there was a substantial change in the particle orientation, especially for an angle between the load axis and the particle axis in the range from 0° to 30°.

Deformation of polycrystalline salt in compression and in shear at 250–350°C

Abstract Dry synthetic polycrystalline salt (NaCl) has been deformed in uniaxial compression and in shear in order to gain insight into the influence of deformation mode on the development of crystallographic preferred orientation, microstructural evolution and mechanical behaviour (flow strength). The experiments were carried out between 250 and 350°C, at strain rates between 10 −5 and 10 −7 s −1 . Under these conditions halite deforms by climb-controlled dislocation creep. In our samples, the presence of deformed grains containing cellular networks of subgrains, and the development of texture are consistent with such mechanisms. The weaker {110} <110> slip plane appears to align parallel to the shear plane and perpendicular to the uniaxial compression direction. In the sheared samples, a <111> maximum is observed parallel to the shear direction. The textures obtained agree favourably with texture simulations. When the mechanical behaviour seen in uniaxial compression and shear is compared in terms of equivalent stress and strain, as defined in the von Mises theory of isotropic plasticity, the uniaxially deformed samples appear to be stronger. From a detailed consideration of the data, it is inferred that the difference in flow strength is largely due to anisotropy resulting from texture development. The results suggest that the assumptions underlying the von Mises theory of isotropic plasticity are not applicable in the present case, and that the associated flow rule does not offer an accurate method of generalizing creep laws for salt under the conditions investigated.

The influence of deformation mode on the dynamic mechanical spectra of lightly plasticised PVC compositions

An assessment was made of the relative merits of various types of deformation mode to monitor variations in relaxation spectra of glassy polymers using dynamic mechanical tests. Rigid and lightly plasticised PVC compositions were used in view of the changes in the α and β relaxations that take place as a result of antiplasticisation and physical ageing phenomena. Large discrepancies were experienced in measurements of the modulus using cantilever deformation modes, while tan δ measurements and calculated values of the activation energies for the α and β processes were found to be less susceptible to variations in type of load imposed on the specimen. The axial pre-loading clamping arrangement was found to be the most accurate in characterising antiplasticisation phenomena, particularly when the static load was large in comparison with the dynamic excitation.