Design and Testing of Pressurized Cellular Planar Morphing Structures

Structural topology optimization for maximum linear buckling loads by using a moving iso-surface threshold method

“…A number of optimization methods have been used for structural topology design considering buckling, e.g., a solid isotropic material with penalisation (SIMP) method, (Bendsøe and Triantafyllidis 1990;Neves et al 1995;Sekimoto and Noguchi 2001;Lindgaard and Dahl 2013), evolutionary structural optimization (ESO) (Manickarajah et al 1998(Manickarajah et al , 2000Rong et al 2001) and a level set method (LSM) (Kasaiezadeh et al 2010;Zhao et al 2011). In this paper, a moving iso-surface threshold method (MIST) recently developed (Tong and Lin 2011;Vasista and Tong 2012) will be used to address the following challenging issues in linear buckling optimization. Topology optimization considering structural buckling is quite complicated and convergence is often relatively poor (Neves et al 2002;Bendsoe and Sigmund 2003;Rahmatalla and Swan 2003;Bruyneel et al 2008) owing to a number of issues, e.g.…”

“…In doing so, the sensitivity analysis of buckling optimization is treated in the same way as that of a free vibration problem, which has been considered one of the error sources in a gradient-based optimization method for buckling analysis (Neves et al 1995;Mateus et al 1997;Bruyneel et al 2008). As explicit sensitivity analysis is not conducted in MIST (Tong and Lin 2011;Vasista and Tong 2012), issue (a) is not involved in the iterative processes.…”

“…Section 2 provides basic formulations for buckling optimization with new constraints on the load-path continuity and the lower bound of the objective function. Section 3 presents the novel response functions, MIST algorithm (Tong and Lin 2011;Vasista and Tong 2012) and implementation in MSC NASTRAN (MSC.Software 2011). In Section 4, numerical results are presented for optimization of in-plane and out-of-plane buckling of a plate.…”

“…2 Problem definitions of finite element based optimization for buckling loads 2.1 Brief overview of MIST MIST (Tong and Lin 2011;Vasista and Tong 2012) involves sequentially finding approximate solutions for optimization based on structural responses obtained in the previous iterations, where features of SIMP, ESO and LSM are combined, i.e., material representation in SIMP (Bendsoe and Kikuchi 1988;Zhou and Rozvany 1991;Rozvany et al 1992), nonexplicit sensitivity analysis in ESO (Xie and Steven 1993;Querin et al 1998) and implicit boundary expression in LSM (Sethian and Wiegmann 2000;Wang et al 2003;Yamada et al 2010).…”

Evaluation of a Compliant Droop-Nose Morphing Wing Tip via Experimental Tests

“…A strain energy-based objective function may lead to a better balance of stiffness and flexibility and may also implicitly consider actuator size and system weight in the design. As evident, further development of the continuum gradient-based topology optimization method is required and given the ability of this method to generate optimum designs from an essentially 'blank canvas' warrants this development, especially for the design of special compliant mechanisms such as pressurized compliant structures [48][49][50].…”