The eccentric check butterfly valve is a butterfly valve that has an eccentric rotating axis. It is not only used as a butterfly valve to control the flowrate or pressure, but also as a check valve to prevent backward flow. A new design process is proposed for designing the valve. First, an optimization problem with a characteristic function is formulated to determine the amount of eccentricity. The characteristic function to be minimized is defined for the flow characteristics. Second, the waterhammer pressure of the valve disc is calculated by waterhammer analysis when the flow stops suddenly. Structural analysis is carried out to evaluate the waterhammer pressure of the valve disc and structural safety. Structural optimization is performed considering the structural safety and the flow characteristics. The process of structural optimization has two steps: topology optimization and shape optimization. Mass distribution of the disc housing is determined using topology optimization. Since topology optimization does not give the final dimensions, shape optimization is utilized to determine the details based on the results of topology optimization. A light design is derived to satisfy the structural safety and the flow characteristics.
Computational occupant analysis has been performed with a pre-determined crash pulse which is produced from a real test. The involved crash components are designed on the basis of the results of the analysis. This method has limitations in that the design does not have much freedom. However, if a good crash pulse is proposed, the occupant's injuries can be reduced more effciently and the body structure can be modified to generate the crash pulse. A good crash pulse is a deceleration curve that minimizes injuries to unrestrained occupants. In this research, a preferable crash pulse is generated by an optimization method called the response surface approximate optimization (RSAO). RSAO is a modified algorithm from a response surface method. The crash pulse is determined to minimize occupant injury while the related physics are satisfied. An RSAO in a commercial code is utilized by interfacing it with an in-house occupant analysis program called SAFE (safety analysis for occupant crash environment). Design of the involved components is carried out on the basis of the generated crash pulse by optimization. The RSAO is also used in this design process. The advantages of the RSAO are investigated as opposed to other design methods, and the results are compared and discussed.
The design process of the motor-driven tilt/telescopic steering column is established by an axiomatic design approach in conceptual design. Since independent design parameters are de ned for improving the performance of the steering system, each detailed design can be carried out independently. In detailed design, occupant safety in a crash environment and vibration reduction are considered. The occupant analysis code SAFE (Safety Analysis For occupant crash Environment) is utilized to simulate the body block test. Segments, contact ellipsoids and spring-damper elements are used to model the steering column in SAFE. The model is veri ed by the result of the body block test. After the model is validated, the energy absorbing components are designed using an orthogonal array. Occupant analyses are performed for the cases of the orthogonal array. Final design is determined for minimum occupant injury. For vibration analysis, a nite element model of the steering column is de ned for the modal analysis. The model is validated by vibration experiments. Size and shape variables are selected for the optimization process. Optimization is conducted to minimize the weight subjected to various constraints.
Multidisciplinary design optimization based on independent subspaces (MDOIS), which is a multidisciplinary design optimization (MDO) algorithm, has been recently proposed. Since MDOIS is relatively simple compared with other MDO algorithms, it is easy to apply MDOIS to practical engineering problems. In this research, an MDO problem is defined for the design of a belt-integrated seat (BIS) while considering crashworthiness. The crash model consists of an airbag, a BIS, an energy-absorbing steering system, and a safety belt. It is found that the current design problem has two disciplines - structural non-linear analysis and occupant analysis. The interdisciplinary relationship between the disciplines is identified. Interdisciplinary variables between the two disciplines are stiffness of the seat back frame and the belt load. The interdisciplinary relationship is addressed in the system analysis step in MDOIS. Prior to each independent subspace design, values of interdisciplinary variables at a given design point are determined in the system analysis step. The determined values are passed to corresponding subspaces, and the subspaces treat the received values of the interdisciplinary variables as constant parameters throughout the subspace design. For the present example, the belt load is passed to the structural analysis subspace and the stiffness of the seat back frame is passed to the occupant analysis subspace. Determined design variables in each subspace are passed to the system analysis step. In this way, the design process iterates until the convergence criterion is satisfied. As a result of the design, the weight of the BIS and the head injury criterion (HIC) of an occupant are reduced while the specified constraints are satisfied. Since the system analysis cannot be formulated in an explicit form in the current example, an optimization problem is formulated to solve the system analysis. The results from MDOIS are discussed.
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