Temperature Dependent Mechanical Behavior of a Locally Restrained Graphite-Aluminum Laminated Plate under Bi-axial Loading

AbstractTemperature-dependent mechanical behavior of a locally restrained metal-matrix composite plate is investigated under uniform bi-axial compression. Thin rectangular plates of angle-ply and cross-ply laminate composed of Graphite-Aluminum composite are considered for the analysis. The plates are assumed to be locally restrained at their corner regions. Temperature-dependent me- chanical properties of the metal-matrix composite are used in the displacement-potential analysis of the elastic response. Results of deformed shapes as well as stress distributions are demonstrated as a function of temperature and fiber-orientation of the laminate

Thermal Ageing Effect on Electro-Mechanical Properties of Work Hardened High Conductive Copper Based Material

High conductive materials may undergo work hardening in the process of manufacturing and utilization as machine parts. Moreover, these materials face various thermal conditions at operational environment. As a consequence, the electro-mechanical properties of these materials get changed, which in turn affect their operational ability as these materials need to maintain high conductivity along with desirable mechanical properties. It gratifies to investigate the effect of thermal ageing on the electro-mechanical properties and microstructure of high conductive copper based material. In this work, the samples are prepared from copper ingot and alloy collected from local market. From the bulk material, long bars are taken, and they are at first homogenized and solution treated, and then they have been work hardened at different level in two conditions i.e., at room temperature and near recrystallization temperature. Thereafter, a series of experiments are carried out to determine the changes in conductivity, micro-hardness, strength, elongation and microstructure of samples as a function of thermal ageing temperature. Most of the mechanical properties after thermal ageing are found to be influenced quite significantly by work hardening.  &nbsp

Measurement of Potential Drop Distribution by Scanning the Closely Coupled Probes Sensor for Sensitive NDE of Shallow Surface Cracks

Highly sensitive nondestructive evaluation of shallow surface cracks is realized through the distributions of d-c potential drop obtained by scanning the closely coupled four-point-probes sensor around the crack. A methodology is developed for evaluating the depth and length of a three-dimensional surface crack from the potential drop profiles measured across and along the crack, where the experimental result is compared with the corresponding prediction of finite element analysis. The highly sensitive characteristic of the measured profiles is also extended to the potential drop imaging for identifying the location of cracks in a clear pictorial form. It is verified that the method is a powerful tool for characterizing very small fatigue cracks (sub-millimeter depth) on the surface of metallic structures

Wet Sliding Wear and Frictional Behavior of Commercially Available Perspex

The tribological behavior of commercially used Perspex was evaluated under dry and wet sliding condition using a pin-on-disc wear tester with different applied loads ranging from 2.5 to 20 N. Experiments were conducted with varying sliding distance from 0.2 km to 4.6 km, wherein the sliding velocity was kept constant, 0.64 ms-1. The results reveal that the weight loss increases with applied load and the sliding distance. The nature of the wear rate was very similar in both the sliding environments in which initially the wear rate increased very rapidly with increasing sliding distance and then progressed to a slower rate. Moreover, the wear rate in wet sliding environment was significantly lower than that under dry sliding condition. The worn surfaces were characterized by optical microscope and SEM. It is found that surface modification has significant effect on sliding wear performance of Perspex

Effect of a DC Field on Temperature Distribution in a Thin FGM Metal Line Subjected to Distributed Local Heating Sources

AbstractThe effect of a direct-current field on the temperature distribution in a thin, non-uniform functionally graded metal line subjected to distributed local heat sources is investigated. The material properties of the metal line are assumed to vary over the span following a linear functional relationship. Bump-like heat sources of different profiles are considered to simulate the condition of distributed local heating of the metal line. The governing differential equations associated with the electrical and thermal problems are derived in terms of variable thermal and electrical conductivity of the material. The solution of the coupled boundary-value problem is then obtained using a finite-difference computational scheme. The temperature distributions in the FGM line are determined for different environmental conditions as a function of intensity of the DC field