说明：  本程序由经典９９行拓扑优化程序改编，可以反向进行反向夹持器的拓扑优化
( A 105 LINE TOPOLOGY OPTIMIZATION CODE BY OLE SIGMUND, JANUARY 2002 This example is selected from the document of "on the design of compliant mecanisms using topology optimization" Note the input displacement is specified as 5e-3mm here )