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Blending polypropylene (PP) with materials such as rubber or filler creates compound PP, which is widely used in auto parts because of its balanced physical properties, formability, and cost performance. Recently non-painting of parts, namely coloring the raw materials, is being investigated as a method of reducing the cost of exterior parts which have conventionally been painted to match body colors, which are mostly metallic now. However flow marks often form in long injection molded parts such as the side protection molding, causing remarkable decreases in exterior appearance quality. This research investigates the influence of metallic coloring of PP material (blending PP and metallic pigment) factors on flow marks, as well as countermeasures for those causes of flow marks. PP and metallic pigment characteristics were the factors investigated to evaluate flow mark level.

Recent growth in automotive applications of magnesium die cast alloys has made the refining and recycling of magnesium scrap a key issue for the automotive and magnesium industries, if growth is to continue. Today, with only a few exceptions, commercially refined and recycled alloy is produced using a variety of flux-based processes. However, fluxless refining, has been the focus of growing interest, particularly for the in-house refining of scrap by the die cast producers. This paper summarizes the results of a study conducted to better understand the behavior of non-metallic contaminants in scrap melts and the requirements for their separation, using argon sparging. Brightness measurements were used to experimentally determine the distribution of non-metallic contaminants within scrap melts both before and after argon treatment.

Creep tests under three-point bending loading were conducted at elevated temperatures for long glass fiber reinforced polypropylene in order to examine the effect of maleic anhydride modification for polypropylene matrix on the creep resistance. The high acid modification (1 wt%) significantly reduces the creep deflection at both low and high sustained loads. The residual tensile strength after 1000 hours creep also increased with an increase of maleic anhydride content. AE observation indicating an occurrence of debonding decreased with increasing acid density. The fractured surfaces show that the interfacial strength between glass fibers and matrix can be increased owing to an increase of maleic anhydride fraction.

Applications of magnesium-based alloys to transmission and underhood automotive components have been limited by creep and bolt-load relaxation. A further concern is the relative expense of Mg alloys, such as AE42, that contain rare earth elements. These alloys still fall short of the performance of 380 Al. A new family of low-cost Mg alloys (ZAC) containing Zn, Al, and Ca has been developed and reported to approach AE42 and to outperform 380 Al; however, it exhibits castability concerns in die casting. This study was designed to evaluate the performance of semi-solid injection-molded (Thixomolded®)1 ZAC8506 bolt-load retention samples at temperatures up to 175°C. The Thixomolding® process has been reported to markedly improve the creep resistance of AZ91D as the volume fraction of solids is increased. The processing conditions were selected to produce bolt-load retention samples having solid fractions of 6% to 37% primary alpha.

The hatchback of Volkswagen's 3 liter car (3 l fuel consumption per 100 km) consists of an inner component of die casting magnesium (AM50) covered with an aluminum panel from the outside. This hybrid design requires a new manufacturing process: The pre-coated magnesium part will be bonded and folded with the bare aluminum part. Corrosion protection is provided by an organic coating system which both protects against general corrosion and galvanic corrosion. The corrosion of the Al / Mg sandwich has been examined with hybrid samples which are similar to the hatchback. Several powder coatings (epoxy resin, polyester resin, hybrid resin), wet paints and cathodic electro-coating paints of different thicknesses and compositions have been applied to the magnesium part. They show that only powder coating provides adequate protection. Galvanic corrosion at the points of attachment of the hatchback might be possible (for example the bolted joint of the hinge).

The increased use of magnesium die-castings in structural automotive components dictates the con-tinuing need for relevant and reliable data. There is virtually no literature relating to magnesium fatigue under corrosion environments. The purpose of the present study is to investigate the effect of an ‘Anomag’ coating on the fatigue and corrosion fatigue performance of magnesium alloys. The coating - ‘Anomag’, is produced by an anodising method and gives excellent corrosion resistance in chemical media. Standard Charpy test specimens of AM50A (50mm × 10mm × 10mm) with smooth surfaces were used for fatigue testing using the three point bending method. S-N curves were determined for uncoated (die cast surface), 5μm and 25μm thick coatings and 5μm and 25μm coatings with organic sealing. The environments adopted were natural seawater, tap water and air. Fatigue test specimens were characterised by X-ray radiography and SEM fractography before and after fatigue testing, respectively.

The use of die cast magnesium for automobile transmission cases offers promise for reducing weight and improving fuel economy. However, the inferior creep resistance of magnesium alloys at high temperature is of concern since transmission cases are typically assembled and joined by pre-loaded bolts. The stress relaxation of the material could thus adversely impact the sealing of the joint. One means of assessing the structural integrity of magnesium transmission cases is modeling the bolted joint, the topic of this paper. The commercial finite element code, ABAQUS, was used to simulate a well characterized bolt joint sample. The geometry was simulated with axi-symmetric elements with the exact geometry of a M10 screw. Frictional contact between the male and female parts is modeled by using interface elements. Material creep is described by a time hardening power law whose parameters are fit to experimental creep test data.

This paper provides a review of the fatigue properties reported in the open literature for die cast magnesium-based alloys. Recently developed fatigue data, in the form of stress versus number of cycles to failure for bending fatigue (R=-1), are presented for die cast AM60B and AZ91D alloy specimens with thicknesses between 1 and 10 mm. The effects of specimen thickness and macrostructural features, such as porosity distributions and surface features (parting line and ejection pin marks), on the fatigue data are discussed.

This paper describes the high-pressure die castability assessment of two high temperature magnesium alloys, AE42 and the AC series alloy. AE42 is a commercially available alloy. Results showed that AE42 was a castable material for use in high-pressure die casting applications, including large transmission components. AE42 was determined to have similar operating/manufacturing costs if produced in equivalent volumes to AZ91D. The AC series alloy is an experimental alloy comprised of AM50 combined with small percentages of calcium (Ca). It was found that the castability of the AC series alloy decreased with increasing calcium content. Over 0.3% calcium content yielded poor castability performance. Selected mechanical and corrosion properties of AZ91D, AE42, AM50 and the AC series alloys were also explored.

The effect of calcium on the creep and bolt load retention (BLR) behavior of AM50 alloy has been investigated. Four AM50 alloys 0, 0.25, 0.56, and 0.88% Ca have been die-cast. BLR-tests have been conducted at 125, 150, and 175°C and preloads of 14, 21, and 28kN. Tensile and compressive creep tests were also conducted at 150°C and initial stresses from 40 to 80 MPa. Both creep and BLR were significantly influenced by calcium content, with increasing calcium content resulting in improved relaxation resistance. The BLR of AM50 with 0.88% Ca was better than that of AE42 at all temperatures although the effect of calcium was temperature dependent. Calcium did not change the sensitivity of BLR to preload, while it increased the relaxation limit (Fr) of AM50 significantly. In addition, calcium improved the creep resistance of AM50 significantly.

A new heat-resistant magnesium alloy (hereafter referred to as “ACM522”) for die-casting based on the Mg-Al-Ca-RE system has been developed by Honda R&D Co. In the 150°C temperature range, the ACM522 alloy yields high creep resistant characteristics which are superior to the conventional AE42 heat-resistant magnesium alloy, and it also exhibits an excellent resistance to both heat and corrosion which can be favorably compared with the A384 general-purpose aluminum alloy. The use of magnesium for oil pans has raised a number of issues such as reduced axial force in the bolted areas and, until now, oil pans made of magnesium had not reached the stage of commercial viability for mass-produced automobiles. The authors applied the ACM522 alloy to develop light-weight oil pans which are 35% lighter than conventional aluminum oil pans.

Weigth saving is more and more recommended due to future demands for low energy consumption. Especially the automotive industry continues to search as diligently as ever for ways to build lighter vehicles. Therefore, the use of light weight metals, preferably aluminum and magnesium is on the rise. This contribution shows effective possibilities to fasten magnesium components, which require special fastening elements, if high stressed and reliable mechanical connections are necessary. Topics are fundamental mechanics of magnesium fastening as well as examples for applications with screws, rivet nut and self piercing rivet.

The effect of strain rate on tensile properties of cold chamber die cast AZ91D, AM60B and AM50A test bars is reported. The strain rate was varied from 15 s1- to 130 s-1, a range typical of deformation and crash. All tests were done at room temperature. The properties measured include fracture elongation and ultimate tensile strength values. The results are discussed in terms of the work hardening characteristics and strain rate sensitivities of the materials, and parameters in a material model suggested by Johnson-Cook have been determined. It has been found that flowstress increases and that elongation is not affected by strain rates from 15 s-1 to 130 s-1. The energy absorption during deformation increases therefore with the speed of deformation, emphasizing the positive properties of magnesium die cast alloys for safety related applications.

To achieve a mass goal and minimize the bell mouthing phenomenon of Passenger Air Bag Housing which takes place when the air bag is in explosive action and detrimental to the safety of passenger side because excessive canister bell mouthing may distort and crash the top surface of instrument panel, a study on the replacing process of a PAB housing to a different material and process was performed. The explosive action of current steel PAB housing was firstly analized to evaluate the reaction forces transferred through the PAB and find out the adaptable material for replacing process. Due to the properties among the die casting alloys, the AM60B alloy was chosen for our new material for PAB housing. Then, stress analysis by the finite element method was performed for a design modification of magnesium one piece housing.

A Draw Bead Simulator (DBS), with modified draw beads, was employed in this study to understand the springback behavior of sheet metal subjected to multiple bending-unbending cycles. The investigations were carried out in both the rolling and the transverse rolling directions on four types of materials: Electro-Galvanized DQ steel, light and heavy gauge Hot-Dip Galvanealed High Strength Steels, and Aluminum alloy AL6111. The sheet geometries, thickness strains, pulling forces and clamping forces were measured and analyzed for the purpose of establishing a benchmark database for numerical predictions of springback. The results indicate that the springback curvature changes dramatically with the die holding force. The conditions at which the springback is minimized was observed and found to depend on the material properties and the sheet thickness. Analysis with an implicit FEM showed that the predicted and the experimental results are in very good agreement.

Tubular bending and hydroforming expansion processes are studied experimentally and numerically in this paper. The experimental results show that the hydroforming process is sensitive to material grades and process variables, and the axial feeding used in this case causes more material deformation near the inner bending surface. Finite element analysis (FEA) was carried out on an S-shape bending and expansion process using the incremental code LS_DYNA. The simulation results successfully explain the phenomena occurring in the experiments. A methodology of analyzing tubular bending process using a One Step FEA code is proposed to improve simulation efficiency. This approach is validated by comparisons with both the incremental FEA predictions and the experimental results. One Step FEA is not only highly efficient but also reasonably accurate in predicting the deformation mode and thickness distributions during the bending operation.

The use of commercial finite element analysis (FEA) software to perform stamping feasibility studies of automotive components has grown extensively over the last decade. Although product and process engineers have now come to rely heavily on results from FEA simulation for manufacturability of components, the prediction of springback has still not been perfected. Springback prediction for simple geometries is found to be quite accurate while springback prediction in complex components fails to compare with experimental results. Since most forming simulation FEA software uses a dynamic explicit solution method, the choice of various input parameters greatly affects the prediction of post formed stresses in the final component. Accurate stress prediction is critical for determination of springback, therefore this study focuses on the effects of some of the simulation parameters such as, element size, tool/loading speed and loading profile.

Present models and methods for simulations of sheet metal forming processes are reviewed in this paper. Because of rapid progress of computer hardware, complex computations, formerly impossible to perform due to high computational cost, are now feasible. Therefore, more realistic and computational intensive models are suggested for finite elements, materials, and frictional forces. Also, simulation methods suitable for sheet metal forming processes are recommended. Four numerical examples at the end of the paper are presented to support the recommendations.

The springback behavior might be different due to different gap clearances between die and punch. A study using FEA simulation is done to investigate the die gap effect. A 3D brick element and an explicit-implicit method are employed to investigate a few simple problems. A draw form, a crash form with an upper pad and a flange form are investigated separately. Numisheet’93 2D draw bending springback problem is also investigated using an explicit dynamic code. Comparisons between springback simulation results on several different die gaps are illustrated. The Kirchhoff assumption of C° shell element and the Mindlin/Love assumption of thin shell element are also examined on different cases. A case study then is performed on a rail type panel. Conclusions and recommendations for future studies are summarized.

{Metal forming process is characterized by large deformation that poses a great challenge for the implementation of contact algorithm. Based on the meshless representation of the geometry, a new contact detection algorithm is presented in this paper. The advantage of this algorithm is that it can handle a wide variety of complicated geometry involved in the forming process. Because only a simple scalar criterion is used, the algorithm is applicable to parallel computing and detection of self-contact. Although the algorithm is derived based on the framework of meshless method, it can be implemented in both finite element and meshless methods.}