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This paper presents an analysis of deformation modes of Forming Limit Diagrams (FLDs) for tailor-welded blanks (TWBs) through designed experiments. Cold rolled steel sheets of different thickness combinations are used in this study. One-step forming of TWBs has the advantage of cost reduction and body weight reduction. Recently, TWBs are being commonly used in car-body panel manufacturing. Most of the previous research work focused only on the effects of laser welding parameters and material properties on the formability of the TWB. However, effects on the FLDs of TWBs are still uncertain. For this reason, a kick-off study on the analysis of different thickness combinations of 0.7mm, 0.8mm and 1.0mm steel sheets was carried out after butt-welding by Nd-YAG laser. Circular grid patterns were printed on the surface of specimens for different testing, like tensile testing and Swift Round-bottom testing.

Diesel vehicles emission is the main contributor to the air pollution in Hong Kong accounting for almost all the particulate and 75% of nitrogen oxides emissions from vehicles. The control strategy of the Hong Kong Environment Protection Department is: Introducing the most stringent practicable emissions and fuel standard. Introducing clean alternatives to reduce the reliance on diesel vehicles Strengthening the inspection on the emissions of motor vehicles Stepping up the enforcement against smoky vehicles Retrofitting of in-use vehicles with locally practicable technology Promoting environmentally friendly driving behavior and awareness of proper vehicle maintenance. This paper summarizes the progress of all the control measures and also reports in details the results and the way forward of the various trials of diesel vehicles retrofit technologies including small particulate traps, oxidation catalysts and ultra low sulphur diesel.

To abate the diesel vehicle emissions, Hong Kong Environmental Protection Department (HKEPD) has implemented comprehensive control measures including retrofitting programs for the pre-1995 light and heavy-duty diesel vehicles. Local franchised bus companies also carried out their own catalyst-retrofitting program in recent years as part of their emission control measures. Before launching the retrofitting programs, we carried out trials to investigate the application issues of exhaust after treatment technology under local operation conditions. Parameters such as diesel catalyst cell density, engine exhaust temperature, backpressure, diesel fuel sulphur content and in-use catalyst durability performance that form the key elements for retrofitting are studied. Also, the in-use catalyst monitoring performance by the use of carbon monoxide (CO) and hydrocarbon (HC) measurement at high idle and dynamometer testing is investigated.

Surface mechanical attrition treatment (SMAT) consists of producing a thin surface layer of compressive residual stresses that prevents crack initiation and retards crack growth during service. The capability for a non-destructive measurement of the compressive stresses is very useful to assure fatigue life of components treated by SMAT in the industrial domain. In this paper, an ultrasonic method based on the longitudinal critically refracted (Lcr) wave is proposed for this purpose. The Lcr wave travels just below the surface of the material, so it may be used to detect subsurface stresses in the structure components. This wave has several advantages over conventional surface waves and bulk waves in detecting the residual stress. The Lcr technique has been applied on the SMAT aluminum alloy specimen to determine the residual stresses in different depths, as well as on the specimens before and after stress relaxation annealing treatment in different zones.

In this paper, the formability of Ti-TWBs at different elevated temperatures is experimentally investigated. Ti-TWBs made of Ti-6Al-4V sheets with thicknesses of 0.7mm and 1.0mm are manufactured. Then, the tensile test and forming test at elevated temperatures, ranging from room temperature to 600°C, have been carried out to determine the mechanical properties and the formability of the prepared Ti-TWBs respectively. The effects of elevated temperatures on both the forming and failure behaviors of the Ti-TWBs are examined by comparing with that of the Ti-6Al-4V base metal. It is found that the formability of the Ti-TWBs at room temperature with a dissimilar thickness combination is lower than that of their base metal, whilst the formability of both the Ti-TWBs and their base metal increases with increasing forming temperature. In addition, failures have often been found at the thinner base metal during the Ti-TWB forming, provided that the quality weld is attained without defect.

Based on the modeling of tire vertical characteristics and steady state cornering properties, the model of tire nonsteady cornering is established in this paper using the tire modal parameters extracted experimentally. The dynamic deformation of tire footprint and the influence of tire width for self-aligning torque are taken into account. The footprint is segmented and the influence of speed on non-steady characteristics is included. The analytical formulae for calculation of transfer-function of lateral force and self-aligning torque with respect to lateral displacement and yaw angle are derived. The non-steady characteristics of tire under different loads can be calculated. The calculated results are consistent with the experimental results in the literature. This shows that the tire nonsteady model can be established conveniently using experimental modal parameters. The dynamic characteristics of tires under different working conditions can be calculated directly.