Yoshio Kojima

CAE (Computer Aided Engineering) has been regarded as a numerical experiment to replace prototyping and experiments. Moreover, the necessity for designers' CAE has recently come under discussion. This refers to the CAE that covers processes such as product planning and grand design. This paper will introduce FOA (First Order Analysis) software as the designers' CAE and address how it can work in the future.

CAE numerically estimates the performance of automobiles and proposes alternative ideas that lead to higher performance. However, most automotive designers cannot directly utilize CAE since specific well-trained engineers are required to achieve sophisticated operations. Moreover, CAE requires a huge amount of time and many modelers to construct an analysis model. In this paper, we propose a new CAE concept, First Order Analysis (FOA), in order to overcome these problems and to quickly obtain optimal designs. The basic ideas include (1) graphic interfaces using Microsoft/Excel, (2) use of sophisticated formulations based on the theory of mechanics of material, and (3) the topology optimization method. Further more, some software prototypes are presented to confirm the FOA method. Moreover, the cross-section generation tool is added to easily create the FOA model from FEM data and to easily evaluate the yielding state. Also a trial study of interaction between FOA and CAE is performed.

In automotive body structural design, Computer Aided Engineering (CAE) has been widely used in order to evaluate noise, vibration, and harshness (NVH). A CAE engineer typically uses a large-scale finite element model exceeding 1 million degrees of freedom to improve the NVH performance criteria. It is, however, difficult for a CAE engineer to propose a good modification candidate for the NVH reduction to an automotive designer, because the FEM calculation is very time-consuming and many design candidates must be considered for a large-scale model. Therefore, quick and effective design calculation procedures are needed to overcome these problems, especially in the recent virtual prototyping development process. In this paper, a new optimal design method using a reduction scheme based on the physical coordinates under many design constraints regarding crash-worthiness is proposed in order to overcome these problems. That is, we determine the appropriate location and additional scalar spring constants by minimizing the acceleration of the observation grid. The effectiveness and availability of this method are confirmed using an example.

Computer Aided Engineering (CAE) has been successfully utilized in mechanical industries. CAE numerically estimates the mechanical performance and proposes alternative ideas that lead to higher performance without building prototypes. Most CAE tools, however, are not utilized due to the sophisticated operations. The concept of First Order Analysis (FOA) has been proposed to provide a new type of CAE for design engineers. In this report, we present a topology optimization method using discrete elements. The basic ideas involve a concept of Product Oriented Analysis (POA) that allows design engineers to easily deal with the optimization scheme. First, the mutual stiffness is defined based on a mutual energy concept. Next, a multi-objective optimization problem to deal with the multiple loading problem is formulated, and the optimization procedure is developed based on the ground structure approach and sequential convex programming. Finally, some examples are provided to confirm the availability of the proposed method.