A micro-tensile testing system has been developed to measure mechanical properties of a thermal SiO 2 thin film. Through the stiffness coefficient calibration of the tensile system in situ, the deformation of the gage section is obtained using a two-serial spring model. A simple gripping method with rapid alignment is presented to improve alignment precision and repeatability of the measurement. Two kinds of specimens, including traditional ones and those with suspended spring beams, are fabricated using inductively coupled plasma (ICP) etching technology. The finished free-standing thermal SiO 2 beams are buckled because of the compressive residual stress. The residual elongation of the beams could be obtained from the original load-displacement curves of the SiO 2 beams. Thus the compressive residual stress, Young's modulus and the fracture strength of the thermal SiO 2 beams were achieved simultaneously from the tensile testing. The measured values of Young's modulus are 64.6 ± 3 GPa for traditional SiO 2 film specimens and 65.5 ± 2.8 GPa for those with suspended spring beams. The measured residual stress is 354 ± 26 MPa and the fracture strength is 426 ± 63 MPa. The measured modulus and residual stress are reasonably coherent with other reports.
A micro-tensile testing system has been developed to measure the mechanical properties of post-buckled silicon dioxide micro-bridge beams. A kind of verniergroove carrier is presented to improve alignment precision and repeatability of the measurement, and the stiffness coefficient of the tensile system is calibrated in situ in order to obtain the deformation of the tensile beams. Through analyzing a series of stress states in the beam over film preparation, post-buckling and unfolding of the beam, the initial residual stress in the film is obtained from the original load-displacement curves. The residual stress of 354 MPa is consistent with that calculated from the theory of finite deflection of buckled beams. Young's modulus and tensile fracture strength are also obtained from the load-displacement curves. The measured modulus and strength are 64.6 ± 3 GPa and 332-489 MPa respectively. The measured properties of the thermal silicon dioxide film are reasonably coherent with other reports.
A three-dimensional (3D) digital image correlation (DIC) method is presented for measuring the deformations of vinyl chloride-coated metal (VCM) multilayer sheets and their composites. The calculations and the principle of strain and deformation measurements using the DIC method are described. A VCM multilayer sheet consists of a substrate [steel plate cold commercial (SPCC) and steel plate cold elongation (SPCE)] and a clad (a VCM film). The corresponding deformations of VCM deep-drawing multilayer sheets (SPCE as a substrate and a VCM film as a clad), VCM nondeep-drawing multilayer sheets (SPCC as a substrate and a VCM film as a clad), nondeep-drawing substrates (SPCC), deep-drawing substrates (SPCE) and clads (VCM films) were captured along the x- and y-directions in uniaxial tension experiments and using the DIC method. The maximal measured strains along the x-direction for the VCM deep-drawing multilayer sheets, VCM nondeep-drawing multilayer sheets, nondeep-drawing substrates, deep-drawing substrates and clads were, respectively, 637.835%, 132.210%, 31.688.632%, 107.102%, and 118.937%. The maximal measured strains along the [Formula: see text]-direction were 739.028%, −11.174%, −9.678%, −13.273% and 12.120%, respectively. These data show that the mechanical properties of VCM multilayer sheets are better than those of their substrates and clads. The effectiveness and accuracy of the presented DIC method for VCM multilayer sheet measurements were confirmed in a series of experiments.
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