Advanced Materials Research Vols. 418-420

Abstract: Due to the significant effect on vehicle lightweight, adhesively bonded joint in structural components is widely adopted in automobile industry in recent years, which leads to the benefits in fuel economy, reduced emissions and driving safety. In this paper, the performances of adhesively bonded joints with three different adhesive types after different temperature treatments are investigated through joint shear strength test. Visual inspection is performed on fracture surfaces after joint failure. Results showed that both low and high temperatures have impact on joint strength and lead to different fracture modes. Stiff and flexible adhesives also result in different fracture surfaces in the overlap zone as the temperature varies.

Abstract: Cold-bent section is one kind economic section molding of low energy consumption and high benefit, it is widely applied in the construction, the astronautics, the light industry and so on many fields. Deformation mechanism of the cold- bent section is extremely complex, relations of deformation strength and energy and steel belt deformation can not described by the simple function. Thus leads to complexity of the roll pass design. Establishing multi-Agent system corresponding with the steel belt characteristic finite strip sets, Introducing characteristic multi- Agent model strategy can intelligentize the condensing data, thus can realize the roll pass design intelligentization.

Abstract: The problems of 3Cr2W8V steel concave die forging production must be solved, such as too many procedures, high cost and mold crack. Through the use of a warm extrusion forming method it could make one-off forming die cavity come true, more practical warm extrusion forming parameters and extrusion die structure parameters were obtained. A suitable lubricant was selected out so that the processed forging die organization was improved and forging streamline distribution was more rational. The service life of forging die increased, and warm extrusion forming technology was applied in the mold production.

Abstract: Effects of deformation temperature and strain rate on deformation behavior of semi-solid ZL201 alloy were investigated on Gleeble3800 thermal-mechanical simulator. On basis of the experimental data of semi-solid ZL201, a model of was established to describe the relationship between the processing parameters and flow stress, which showed that the experimental results and calculation ones fitted well. The suitable conditions of this model for semi-solid ZL201 alloy were that the temperature range was 547°C-649°C and that of the strain rate was 0.1 s^-1-5s^-1.

Abstract: This experiment was aimed to investigate mechanical properties of aluminium-alumina welding by using friction welding. Effect of feed rate on hardness and shear strength of welding interface were determined. Cracking of alumina ceramics was also investigated. In addition, this research is to define and analyse temperature of an interface and deformation rate of aluminium during process. It was found that welding temperature increased with increasing feed rate. Increasing feed rate resulted in increasing of deformation rate and flow of aluminium lead to incresing of welded area. After welding, hardness of aluminium near interface was increased from 44-46 HV to 52.6-55.7 HV. Hardness of aluminium decreased with increasing distance from interface. The maximum shear strength was 29 MPa obtained from 0.3 mm/s feed rate. The minimum shear strength was 3.1 MPa obtained from 0.1 mm/s feed rate. Shear strength was deteriorated by both mechanical and thermal strength. It can be clearly seen that increasing feed rate increase welded area, resulted in higher interface strength.

Abstract: Work piece surfaces produced by wire EDM can exhibit surface alterations resulting from rapid heating and quenching during machining. The thermally altered layers have tremendous impacts on mechanical properties of machined product. Multi-cutting passes of brass wire into stainless steel sheet SS304 has been suggested in this paper. Three holes was machined at one cutting passes, two cutting passes and three cutting passes respectively and the effect on surface roughness of machined steel was investigated. Visual micro-structure study has been done to explore the existence of white layer and Heat Affected Zone (HAZ) layer. Based upon experimental result, the surface roughness is decreased with the increment of cutting passes. The white layer only formed at first cutting part and did not appear at two and three cutting passes.

Abstract: The increasing interest in structured sheet metals for lightweight constructions and automotive can be seen in recent years. The driving force of this trend is higher stiffness of structured sheet metals in comparison to smooth sheet metals. The structured sheet metal is a sheet metal with a periodical three-dimensional geometry, which is manufactured by hydroforming process. The improved properties of this sheet metal allow the weight reduction of car components and lightweight structures. The purpose of this study is the determination of the force requirements by air bending of structured sheet metal and an analysis of influence factors on the bending force. Moreover an improvement of an analytical calculation of the maximal force for air bending of structured sheet metals is presented. In this work the steels DC04, DX56D-Z and X5CrNi18-10 were investigated. The results have shown that the bending position and the structure location have a big influence on the bending force. All investigated materials have similar behaviour. The largest and smallest bending force can be seen in the bending positions III and II respectively. At the structure location “negative” the maximal bending force is smaller than at the structure location “positive”. The results of the different calculation methods were compared to the experiments. The developed analytical approach provides more precise results than conventional method. In contrast to existing analytical calculation methods it takes into account the influence of the structure location and bending position of structured sheet metals on the bending force

Abstract: Synthesis of poly(L-lactic acid), PLLA, in a mass scale production using 2-steps direct polycondensation methods was investigated. One hundred kilogram of L-lactic acid was esterified in a designed reactor under reduced pressure at elevated temperature in the first step, followed solid state polymerization, SSP. The synthesized PLLA from both laboratory (5 g) and mass (100 L) scales show comparable melting temperature, Tm (151 – 172 oC) and molecular weight (Mn) (10,000 -32,000) at the similar polymerization conditions. The appearances of synthesized PLLA are yellow-white solid powder. The results show high potential to produce environmental friendly polymer, PLLA, using non-complex facilities process.

Abstract: The experiments were carried out in the paper to investigate the effect of adding hydrogen in titanium alloy TC4 on its machinability. The hydrogen contents selected were 0, 0.25%, 0.49%, 0.63%, 0.89% and 1.32%, respectively. Experiments with varing hydrogen contents and cutting conditions concurrently. Experimental results showed that the cutting force of the titanium alloy can be obviously reduced and the surface roughness can be improved by adding appropriate hydrogen in the material. In the given cutting condition, the titanium alloy TC4 with 0.49% hydrogen content showed better machinability.

Abstract: This paper deals with the analytical and experimental vibration analysis of the single lap adhesive joint with non-uniform adhesive thickness . In the theoretical part, an analytical modal is described and a motion equation is built. A joint consists of two different adherends are bonded over a certain length by a viscoelastic material, epoxy resin. Adherends are modeled as Euler-Bernoulli beams. Both ransverse and axial deformation of adherends are considered in deriving the equations of motion. In the experimental part, the steel use Q235, the aluminium use 6016-T4 and the adhesive use ESP110 and AV138, epoxy resin. Dynamic responses of the joints are investigated using the hammer test technique, natural frequencies and model shapes obtained by using an accelerometer depended on the accelerometer location in the system, which is attributed to its mass contribution to the overall system mass. The investigates are also carried out using the finite element method(FEM) and simulated with ABAQUS. Both results show that resonant frequencies decrease with the slant angle increase.