<div class="section abstract"><div class="htmlview paragraph">Many elastomeric components in automotive industry applications are subjected to dynamic service loads. Fatigue must be a consideration in the design of these components.</div><div class="htmlview paragraph">The two approaches in rubber fatigue analysis discussed in this study are the conventional crack initiation approach, based on continuum mechanics parameters versus life, and the crack growth approach, based on fracture mechanics parameters. These methodologies are demonstrated for a passenger vehicle engine mount here. Temperature effects are not considered since testing was performed at ambient room temperature and with a low frequency, typically less than 5 Hz.</div><div class="htmlview paragraph">The promising methodology for fatigue life prediction, discussed in this paper, is a critical plane approach based on crack energy density. Rainflow cycle counting method and Miner’s damage rule are used for load cycle characterization and damage accumulation respectively. A fracture mechanics approach is implemented based on specimen crack growth data.</div><div class="htmlview paragraph">This methodology is validated with component testing under constant amplitude experiments. Results are investigated through analysis of critical stress locations hot spots, life values, and strain states. Comparative results are presented. Numerical results show reasonable correlation with experimental data.</div></div>

The paper details the studies carried out on a dual-size particulate composite prepared by stir casting using A 356 aluminum alloy and B4C powders. Three composite compositions, viz., A356 plus 2% B4C (44µm size and 105µm size in 1:1 ratio), 4% B4C (3:1 ratio), and 6% B4C (1:3 ratio) were cast in finger molds, from which test specimens were prepared for hardness and tensile tests as well as for metallography. Vickers hardness tests, tensile tests and microstructure analysis using an optical microscope were conducted. The results obtained indicated that the B4C particles were evenly distributed in the alloy matrix. EDS also revealed the presence of B4C in all the three composites.  In general, the hardness and tensile strengths increased with increase in concentration B4C powders. While the increase in hardness was increases less than 15%, there was significant increase (more than 35 %) in tensile strength. However, the ductility represented by % elongation, which was already very low in A 356 cast alloy (24.2%,), further decreased in composites. Tensile fractography results shows inter crystalline fracture where the breakage in the B4C particle instead of deboning were observed.

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Tests have been carried out to determine the stress corrosion susceptibility of Al‐4.4 a/o Xn alloy in the aged condition. Flat ribbon specimens were tested in aqueous solutions containing 3.5% NaCl at a constant stress of 5.76 kg/mm2 (32% of UTS). Polarisation studies carried out on the stressed and unstressed specimens reveal that the Tafel slopes have a much lower value in the stressed condition. The susceptibility to stress corrosion increases with the test temperature. An equation of the type Z=K. exp (—E/RT) with reciprocal life Z and test temperature T, is found to fit the data from which the value of the activation energy is found to be ca. 20 kcal.mol−1.