In this review,a critical look at the research progress of experimental solid mechanics in China for the past years is presented.Issues are discussed of the discovery and development of new fundamental methods and techniques versus performance benchmarking for many of their applications.Included herein are photoelasticity and various forms of modern photomechanics,acoustical techniques,image processing and videometrics,radial and spectrum techniques,and experimental mechanics on micro/nano scale.It is also noticed that both the ever developed instrumentation and specialized synthetical techniques have played important roles in advancing experimental mechanics in scientific researches and industrial applications.Finally,an attempt is made to look into the future of experimental solid mechanics with personal opinions offered on what the future trends will be for the researches in the field.
We propose a substrate-free focal plane array (FPA) in this paper. The solid substrate is completely removed, and the microcantilevers extend from a supporting frame. Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature: the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements: two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 μm 2 are implemented in the proposed infrared detector. The noise equivalent temperature difference (NETD) values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 μm 2 has a potential of achieving an NETD value of 10 mK.
