Special Issue on Multi-Scale Experimental Measurements in Mechanics

Abstract

The development of micro/nano science and technology in recent years has created new challenges to the traditional macro-scale based experimental measurement. As such, multi-scale experimental measurements in mechanics have become a key area of research. Both the metrology and its applications have drawn great interest from researchers in related fields and have been progressing rapidly. It is our pleasure to present the nine papers in this special issue, entitled “Multi-Scale Experimental Measurements in Mechanics.” The special issue attempts to gather papers in the developments of multi-scale metrologies and related applications. It covers a range of topics to reflect the recent advances in optical measurement methods, non-destructive techniques, mechanical behavior characterization under different high resolution microscopes, fabrication techniques on micro-deformation sensor, etc. A brief introduction of these papers is as follows: In regard to multi-scale experiments including uniaxial tensile testing, in situRaman spectroscopy and scanning electron microscopy, Wei-Lin Deng et al. investigated the deformation in multi-scale and interfacial mechanical behavior of carbon nanotube fibers with multi-level structures. A twolevel interfacial mechanical model is presented to analyze interfacial bonding strengths of mesoscopic bundles and microscopic nanotubes. This study shows that properties of the multi-level interfaces are critical factors for determining fiber strength and toughness. With the aid of the atomic force microscopy (AFM) indentation system, Dongchuan Su et al. studied the near-surface elastic modulus via force-penetration curves acquired during indentation. An analysis algorithm is proposed based on the secant modulus method to extract the true penetration depths from force-displacement curves in AFM indentation testing. The results show that the AFM indentation method is capable of producing high spatial resolution maps of the elastic modulus with small forces and shallow indentations. MEMS sensors are typically fabricated out of materials that are mechanically sound at the microscale, but can be relatively poor electrical conductors. For this reason, areas ofMEMS are coated with various thin metal films to provide electrical pathways. These films, however, adversely alter resonant properties of a device. The paper by Pryputniewicz reviews a theoretical analysis of the effect that thermoelastic internal friction has on the Q-factor of microscale resonators and shows that the internal friction relating to TED is a fundamental damping mechanism in determination of quality of high-Q resonators over a range of operating conditions. As a method for measuring full-field out-of-plane displacement, projection moire provides high quality results with simple test setup. B. Gulker et al. implemented a projection moire system in low-velocity impact testing using an image processing program. Results from the projection moire experiments agree reasonably well with those obtained from the commonly used load cell method. The technique is further applied to composites with various microstructures. Y.R. Zhao et al. developed the electron grid fabricating technique by using a common scanning electron microscope (SEM). An error analysis for the multi-scanning grating was Y. Kang School of Mechanical Engineering, Tianjin University, Tianjin, China