Tensile Strength Properties of Tropical Hardwoods in Structural Size Testing
In Malaysia, there is no research done on the tensile strength of structural size timber. The tension stress found in the Malaysian code of practice, MS 544: Part 2: 2001, was not determined directly and it was taken as 60% of the bending strength values of small clear specimens. This paper presents the results of the tensile test on structural size timber specimens from selected Malaysian Tropical hardwoods namely Kedondong (Canarium spp), Keruing (Dipterocarpus spp) and Bintangor (Calophyllum spp) under the strength group SG5. A special tensile grip was fabricated using the model suggested in ASTM D198 and the tests were also conducted according to ASTM D198. The tensile strength characteristics evaluated include tensile strength, modulus of elasticity and Poisson’s ratio, and the data were analyzed statistically. In this study it was found that the grade stresses for structural size specimens were higher than that published in the Malaysian code of practice. Index Term— tensile strength, structural size, Malaysian
Reliability Analysis of Timber Roof Truss Systems using Genetic Algorithm
Structural reliability analysis was carried out on the Mansonia altissima timber, to ascertain its structural performance in timber roof truss system. Structural analysis of the timber truss was in accordance with Eurocode 5 (2004) and was carried out under the Ultimate Limit State of loading. A developed MATLAB (2010) programme was employed for reliability analysis of the timber roof truss of Mansonia altissima timber so designed, to ascertain its level of safety using GA-based First-Order Reliability Method. The uncertainties in the strength and load variables were accommodated in the reliability analysis. The result of the analysis revealed that the Joint failure mode is the critical safety index that is minimum safety index among the failure modes of the truss under the design conditions. The Mansonia altissima timber was found to be a satisfactory structural element for timber roof truss at depth of 75mm, breadth of 50mm and under the ultimate limit state of loading with the corresponding of 2.58. Sensitivity analysis proves that the degree of reliability of the timber roof truss can be improved if crosssections of species, diameter of nail at joint, pitch of truss and loadings are suitable selected.
The osprey process: principles and applications
Spray forming in the Osprey mode involves the sequential stages of atomization and droplet consolidation to produce near-net shape preforms. This review traces the history and development of the process with particular reference to the processing science base and attendant metallurgical principles. The process has been scaled up for the fabrication of tubular and billet-shaped products in stainless steels, superalloys, cast irons, tool steels, aluminum alloys, and copper alloys. Alloy development via spray forming has resulted in improved mechanical properties, compared to ingot metallurgy