Optimization Design Research On Expansion Joint Bellows

Metal bellow expansion joint (expansion joint for short) is the key part of modern thermal pipe systems and equipments with functions of displacement compensation, vibration and noise reduction and sealing. It is currently used in various industrial sectors, such as mechanical, power, thermal pipe system, shipping, construction and metallurgy industries. Bellows are the basic units of an expansion joint. In the process of bellows design, because many influencing factors (pressure, temperature, compensation, strength, rigidity, fatigue life, stability, etc.) should be taken into consideration, it is difficult to find out optimal structure dimensions by means of manual calculation according to tradition design methods. Adoption of optimization design hi the computer aided design of bellows can reduce developing cost, optimize structure and increase market competitive capacity of the products. Furthermore, it can result in optimal products. Therefore, it is very important to do optimization design research on bellows.In this research paper, through analysis of structure parameters, design theories and equations of bellows, independent parameters affecting performances of bellows were used as design variables. Boundary and performance constraints were determined on the basis of the newest edition of Standard of Expansion Joint Manufactures Association of American EJMA-98 and National Standards of China GB/T12777-1999, Metal Bellow Expansion Joint Common Technical Conditions. Bidirectional searching was performed with a multi-object function of single wave compensation and mass. Specific data for design were dealt with programming process. And mathematical model of optimization design of expansion joint bellows was set up. In order to solve the mathematical model, optimization method of mixed discrete variable combination, mainly based on mixed discrete method, was adopted. By using principles of mixed discrete method and supporting auxiliary functions, such as quadric curve acceleration search, hem search and final reflection technology, the efficacy of mixed discrete method was improved and relatively optimized results were achieved.Practices of the optimization design system of expansion joint bellows in Chongqing Sichuan Instruments Company NO. 7 showed that the software can satisfy practical demands, shorten product developing cycle significantly, reduce product cost, and increase company's developing capacity of new products. Therefore, this research has a broad prospect of application and a high value of popularity.