The successful topology optimization of continuums inspired from the study of the optimal thickness distribution of elastic plates [
1] has led to the successive development of several topology optimization models, such as the homogenization method [
2], solid isotropic material/microstructure with penalization (SIMP) method [
3–
5], rational approximation of material property method [
6], evolutionary structural optimization (ESO)/bidirectional ESO (BESO) [
7–
9], level set method (LSM) [
10–
14], independent-continuous mapping method [
15], moving isosurface threshold method [
16], stiffness spreading method [
17,
18], and moving morphable component/void method [
19,
20]. The most mature method is SIMP, which has been successfully implemented in commercial software systems, such as OptiStruct, Tosca, and ANSYS. SIMP has been widely used worldwide, especially after Sigmund published the 99-line MATLAB code [
21]. It provides an efficient way for new researchers to accept and start their work in topology optimization for continuums. ESO, which was first proposed by Xie and Steven [
7], uses a similar idea to that of SIMP. The idea is to find an appropriate way of material distribution in the design domain. Later, Refs. [
8,
9,
22] proposed BESO, which solves the drawback of ESO that a material cannot be added back into a structure after it is deleted. ESO/BESO has a clear concept of updating a structure to achieve optimum design, and it is easy to understand and implement. It has also been widely studied and implemented in the topology optimization tool Ameba.