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Recent developments in a NIST sponsored program on Design, Non-Destructive Evaluation and the Manufacturing Sciences (being conducted at Iowa State and Northwestern Universities) have led to the realization of a new paradigm for the design of safety critical components made by metal casting. The paradigm is based on the simultaneous integration of design for casting, design for fatigue performance and design for inspection. In a concurrent environment, foundry process simulation is used to predict an array of porosity related defects in the subject casting. The probability of detection of these defects is investigated with a radiographic inspection simulation tool (XRSIM). The likelihood that the predicted array of defects will lead to a failure is determined by a fatigue crack growth simulation. When properly utilized, this kind of system gives visibility to casting manufacturing, performance, and inspectability issues during the earliest stages of product definition.

The occurrence of porosity during metal solidification is one of the major issues that impact the quality of castings. Quantitative information on the development of porosity is particularly important for safety critical components, such as automotive chassis parts and airframe primary structures. In this paper, we present two approaches to predict the location and volume fraction of porosity for aluminum alloy A356. In the first approach, the application of Neural Networks to predict porosity is examined. Results are compared with the established criteria functions and reported experimental findings. Neural Networks are shown to predict the occurrence of porosity with higher confidence than the existing thermal parameter based criteria functions. In the second approach, microporosity evolution is modeled mathematically.

Minimization of part variation has been a challenging topic for both researchers and engineers. Variations in final stamping parts could come from numerous sources such as incoming material, lubricant, processing parameters, environment, automation, etc. Identifying the cause of the variations is not only time consuming, but also a continuously changing process. In this paper, experiments are reviewed which were conducted to examine the feasibility of implementing closed-loop process control to reduce dimensional variations on an in-production 3D part. Specifically, the effects of punch force (PF) and binder force (BF) on part dimensions are studied. For our particular application, proper control of both PF and BF is necessary to control the dimensional variations of the part.

Advanced high strength steels (AHSS) are particularly attractive to automotive industry. Stamping AHSS parts, however, results in accelerated die wear problems which could emerge after few thousands of stampings. The existing wear testing methods are either not suitable for charactering die wear in stamping or requires significant capital investment. The first generation of strip-on-cylinder wear test apparatus which can efficiently and economically characterize die wear is introduced in this paper. Different measurement methods were compared and white light interferometer with nanoscale accuracy was chosen to determine the wear volume due to its overall advantages. Based on the strip-on-cylinder wear test apparatus, a design of experiments study analyzing the effects of contact pressure, sliding speed and hardness of the die material on die wear was conducted and the results were discussed.

Tailor welded blanks offer an excellent opportunity to reduce manufacturing costs, decrease vehicle weight, and improve the quality of sheet metal stampings. However, tearing near the weld seam is a concern in Tailor Welded Blanks due to material changes in the fusion and heat affected zones of the weld. Therefore, data is required such as the potential strain of the material in these areas to use in the process design. For example, Cao and Kinsey proposed a modification to the deep drawing process where segmented dies with local adaptive controllers clamp adjacent to the weld line during the forming operation thereby reducing the strain in the material near the weld seam and in turn the concern of tearing failure. In order to aid in the design process for this modification, an understanding of the effects of the welding process on material changes near the weld seam is essential.

Tailor welded blanks offer a unique opportunity to reduce manufacturing costs, decrease vehicle weight, and improve the quality of stampings through the consolidation of multiple formed, then welded, parts into a single stamping. However, tearing near the weld line often occurs in this type of blank when formed with a traditional deep drawing process. Therefore, some adaptation to the existing sheet metal forming process must be developed in order to reap the numerous benefits available from tailor welded blanks. In this paper, numerical simulation are presented for a newly contrived tailor welded blank forming process where several hydraulic mechanisms apply distinct clamping forces along the weld line during forming. Excellent results demonstrate the effectiveness of the proposed method.

An automotive part formed by 10-step drawing has been simulated by finite element method aiming to reduce forming steps. The reduction of forming steps can be achieved by optimum design of tooling shapes and other process parameters per each step. The ultimate goal will be to apply the derivative based optimization scheme or any knowledge-based system to these kinds of multi-step forming problems. However, as an initial step, we determined the minimum forming steps and optimum tooling shapes using heuristic manner, insight, design rules and testing with finite element analysis incorporated with a damage model. As a result, the 10-step drawing is reduced to 6-step drawing as a practical optimum solution.