Papers by Keyword: Shape Optimisation

Abstract: LAU-7 missile launcher housings, which are fitted to most Royal Australian Air Force (RAAF) F/A-18A/B aircraft, can experience cracking in the guide rail. This paper covers the design, manufacture and validation of a life extension repair for cracked launcher housings. The repair development uses DSTO's rework shape optimisation technology and fatigue testing capabilities. The rework design reduces peak stresses by 33 %, resulting in significant fatigue life enhancements, as demonstrated by representative coupon testing. A special manufacturing jig has been designed and transitioned to the RAAF, which has used it to repair housings. These housings have performed well in flight tests, with no cracking detected.

Abstract: Bimetal actuators are frequently used in engineering applications. The literature for the design of bimetal actuators recommends only approximate analytical formulas for various bimetal structures, all with constant section on the entire length. No reference was found for bimetals with variable cross-section or bimetals shape optimization. Topology and shape optimization specialized software packages are not always an available or easy to use option. The paper presents a Finite Element Analysis, FEA, for a U-shaped bimetal with equal legs, considering both mechanical and thermal loads. FEA modeling aspects and some suggestions considering possible new shape modifications for this type of actuator are discussed.

Abstract: Study on the flexible structural shape optimization problem under dynamic loading conditions. The dynamic loads are transformed to equivalent static loads (ESLs), and then the static response optimization can be used for dynamic response optimization. A structural shape optimization model, which has been established by ESls method, is utilized to design the flexible components in the multibody dynamic system. A shape optimization for a four-bar linkage had been generated by using the ESLs method, and the results indicate that there are noticeable improvements in the total mass and the maximum stress.

Abstract: To decrease the energy loss when the crane dolly climbing and smooth its move track, the arch curves of girder were studied. Geometric model of the structure was simplified reasonably according to crane bridge structure characteristic, and the finite element models of the girder with different arch curves were established. The downwarping values of the girder with different arch curves under the rated load were obtained by simulation analysis, and further the move track of the crane dolly could be drawn. Also, the advantages and disadvantages of the arch curves were discussed. Taking maximum smoothness of the move track of the crane dolly as research object, a better arch curve was obtained by shape optimization. The research can provide a basis and reference for the arch curve design of the crane girders.

Abstract: In this study, we restrict our attention to shape optimization of a body immersed in the Navier-Stokes fluid flow. The formulation and numerical results of the proposed method are presented. The proposed method is based on an optimal control theory. The optimal state is defined by the reduction of drag forces subjected to the immersed object. The cost functional should be minimized is governed by the Navier-Stokes equations. The shape sensitivity analysis of the cost functional was derived based on the adjoint method. Finally, a numerical example is given to show the feasible for the proposed algorithm.

Abstract: The paper presents application of damage tolerance optimisation principles to the design of industrial components. It is illustrated via design optimisation of a Fuel Flow Vent Hole (FFVH) located in the Wing Pivot Fitting (WPF) of an F-111 aircraft. The aim is to determine the shape of the cutout that will maximise its residual strength under the operating loading conditions. Damage tolerance shape optimisation is performed using a heuristic optimisation method known as the ‘Biological algorithm’. The maximum stress intensity factor (SIF) for all of the cracks around the boundary of the optimal cutout is found to be significantly lower compared to that of the initial shape. This shows that an improved residual (fracture) strength is achieved for the optimal designs. The variability in SIF around the cutout boundary is reduced, thereby making the shape more evenly fracture critical. The shapes of the residual strength optimal vent holes are found to depend on the initial crack sizes. It is also shown that a damage tolerance optimisation additionally produces a lighter WPF component design, which is highly desirable for aerospace industries.

Abstract: At present the flat plunge pool and inverted-arch plunge pool are usual plunge pool shape styles in high dam construction. we improve the plunge pool shape according to the study of special flow pattern in the plunge pool and the plunge pool scour mechanism, the high-speed submerged jet diffusion rule in plunge pool, impingement pressure variation rules with the jet flow route changment and some other hydraulic factors, combining with a series of scour experimental results. We analyze the specific situations in the transverse profile and longitudinal profile of the plunge pool respectively and then make corresponding changes. The creative longitudinal profile curve of the inverted-arch plunge pool make a double inverted-arch plunge pool, which makes the hydrodynamic elements and the structure of the plunge pool are in a harmonious state ensuring the safe operation of the plunge pool.

Abstract: This paper highlights a two-level optimization process combined with ant colony optimization algorithm (ACO)，which is applied to design the shape of the transmission tower structure, and compiles optimization design procedure for the solution of the structure shape with the MATLAB language. By comparing the different methods of the transmission tower structure optimization design, the ACO algorithm is demonstrated to be more accuracy and practical in dealing the complex optimizations problem, i.e. the combination of continuous variables and discrete variables. These calculation examples illustrate that the two-level optimization method is reliable and versatile.

Abstract: This paper presented a new mild steel slit damper(SSD). The new shape was parabolic according to all the cross section having the same maximal stress, and the elastic stiffness and yield displacement formula were derived. Finite element analysis showed that the parabolic shaped damper had a more reasonable load - displacement curve compared with the previously proposed shape. The theoretical stiffness and yield displacement were consistent with the results by finite element method (FEM), and that indicated the presented design method was simple and feasible.

Abstract: According to anti-seismic design principle of strong column and weak beam, and of strong joint and weak member, reduced beam section(RBS) is often used to shift away plastic hinge from end of beam to weaken region of the beam. Reduced beam section with cut web are analyzed by non-linear finite element method(FEM) in this paper. Two kinds of effective suggested joints of reduced beam section(circled hole and long-circled hole) are put forward by comparing the results of mechanical behavior of reduced beam section with which of traditional RBS, including of ultimate load-carrying capacity, Von-mises stress distribution and the place of largest stress of beam end of the beam-column joints. A proposed seismic design method is put forward according to related chinese codes.