Applied Mechanics and Materials Vols. 496-500

Abstract: A numerical model of the tailored hot stamping process was developed in the framework of the commercial FE code ForgeTM and accurately calibrated in order to take into account the influence of applied stress and strain on the phase transformation kinetics. The calibration was carried out by introducing in the numerical model data on the shift of the TTT curves due to applied stress and the transformation plasticity coefficients, which were obtained through an extensive dilatometric analysis. The numerical model was validated through a laboratory-scale hot-formed U-channel produced using a segmented die with local heating and cooling zones. The predicted distribution of Vickers hardness and evolution of microstructure given by the numerical model was compared with the experimental results to show the significant predictive improvements introduced by considering the influence of the transformation plasticity and deformation history on the phase transformation kinetics.

Abstract: Firstly, a two-level optimization procedure for composite structure is investigated with lamination parameters as design variables and MSC.Nastran as analysis tool. The details using lamination parameters as MSC.Nastran input parameters are presented. Secondly, with a proper equivalent stiffness laminate built to substitute for the lamination parameters, a two-level optimization method based on the equivalent stiffness laminate is proposed. Compared with the lamination parameters-based method, the layer thicknesses of the equivalent stiffness laminate are adopted as continuous design variables at the first level. The corresponding lamination parameters are calculated from the optimal layer thicknesses. At the second level, genetic algorithm (GA) is applied to identify an optimal laminate configuration to target the lamination parameters obtained. The numerical example shows that the proposed method without considering constraints of lamination parameters can obtain better optimal results.

Abstract: Cellulosic fibers, as the most abundant biopolymer on earth, are attracting more and more interesting to be absorbent for ion removal from aqueous solution due to its biodegradability and renewability. In this paper, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride was used as functional agent to modify the cellulosic fibers to be absorbent for Cr (VI) in aqueous solution. Our attention in this work was aimed at the influence of mechanical refining treatment before graft on the modification as well as the absorption capability of modified fibers. The modification was carried out using refined fibers and raw fibers. The modified fibers were verified by IR analysis. The results showed that in isopropyl alcohol solution and under alkaline condition, the functional agent can be grafted onto fibers. The mechanical refining treatment of cellulosic fibers before modification can improve the grafting efficiency. The absorption capability of modified treated-fibers for Cr (VI) from aqueous solution is higher than that of modified untreated-fibers. More hydroxyl groups on the surface of fibers after mechanical refining treatment is the reason for higher absorption capability of modified treated-fibers and higher grafting efficency.

Abstract: Mechanical behaviors and thermoforming features of plastic material PMMA-IRK-304 used in-mold decoration are studied in this paper. Dynamic mechanical analysis experiments, uniaxial tension tests at several high temperatures and different stretching velocity were carried out to analysis and explain the phenomenon of yielding, strain softening and strain hardening. Results showed that the glass transition temperature range of PMMA-IRK-304 films was suitable for thermoforming of in-mold decoration.

Abstract: Hybrid laser-Arc welding was to weld 20 mm thickness high nitrogen austenite stainless steel plates. Microstructure, hardness, mechanical properties and fractography of welding joints were researched. The results showed that the microstructure of heat affected zone and weld metal is austenite and δ-ferrite, and the heat-affected zone of welding joints is Narrow, its softening zone is smaller, the hardness is more uniform, the tensile strength of welding joints is 93.8% of the base material, fractured in the weld zone. The tensile fractography are obviously dimple.

Abstract: Systematic testing methods of the performance of diamond/metal composite drilling segments (impregnated diamond cutters) have not come into being. This article tries to test the mechanical properties, structures and component of a certain number of impregnated diamond cutters; focuses on analysis of the relationship between the performance of typical composite diamond cutters and materials’ structures, intends to study the testing methods of impregnated diamond cutters’ performance.

Abstract: A three dimensional numerical simulation model of metal rolling formation is developed from the theoretical model. In this theoretical model, the two variables of element deformation and temperature variation are placed in a variable matrix. The thermal elastic plastic rigid matrix and heat transfer rigid matrix are placed in the same expansion rigid matrix. Furthermore, the numerical simulation analytical model developed in this paper was used to simulate aluminum strip rolling.

Abstract: Press-extrusion forming is a combined extrusion process for forming embossment on metal sheets. A series of simulations on embossment forming using the program DEFORM were carried out. It is shown that the optimal process, the suitable die structure and the friction conditions can form embossment on the stamping part with good dimensions. The experiments conducted in the present study not only validated the finite element analysis but also confirmed the efficiency of the suitable die structure in helping the embossment formation.

Abstract: Following the high quality of life that people pursue, the requirements to air and environment are stricter. People value the quality of sleeping and public safety, thus they pay more attention to prevent noises. Noise makes people weary and distracted, and may eventually result in accidents. Therefore, this study uses polylactide fiber (PLA) and low melting point polylactide fiber (LPLA) to make sound absorbent PLA/LPLA plates, after which the tensile strength, softness, and sound absorption of the plates are evaluated.

Abstract: In recent years, as global technical progress grows, many mechanized machines are developed continuously. Mechanization has substituted for manpower in many factories for promotion of production efficiency, leading to mechanical noise happening more severely. If people are subjected to noise pollution for long term, they would happen dysphoria and absent mindedness, resulting in accident occurrence. Therefore, how to effectively reduce noise pollution becomes an urgent subject. Moreover, rapid population development and fast-growth economy raise consumption in every country, driving industry into high-production and high-consumption times and meanwhile generating much of wastes. In order to achieve sustainable development, these wastes should be recycled effectively. Therefore, 20 wt% recycled PET fibers were added in this study. This paper mainly used 3D and 15D Nylon fibers (70, 60, 50, 40, 30 wt%), low-melting PET fibers (10, 20, 30, 40, 50 wt%) and 20 wt% high-strength PET fibers, to fabricate Nylon 6/Low melting PET/ Recycled high-strength PET nonwoven via needle-punching process. After that, tensile strength, air permeability and sound absorption coefficient property of resulting nonwoven were tested and then evaluated respectively.