In-situ testing device for micro-mechanical properties of materials under tension-shear combined loading mode

Abstract

The invention relates to an in-situ testing device for micro-mechanical properties of materials under a tension-shear combined loading mode, and belongs to the in-situ test field of mechanical properties. A tension module and a shear module are composed of a motor power assembly, a transmission and execution assembly, a clamping support assembly, a signal detection and control assembly respectively. The shear module also comprises a piezoelectric driving assembly capable of applying high-frequency shear fatigue loading. A coreless rotor direct-current motor is connected with a planetary gear reducer and is connected with a precision bi-directional ball screw through a worm and gear transmission component; and square nuts connected with the ball screw nuts are supported and guided through guide rails at the two sides. Two loadings are respectively collect force and displacement signals by a precision force sensor and a linear motor power assembly potentiometer. The in-situ testing device is smart in size, compact in structure and high in test precision, can realize the tests of tension and shear loadings at different strain rates and stress ratios, and can be compatible with loading platforms of microscopic imaging equipment such as metallographic microscopes and the like.

Description

[0001] technical field [0002] The invention relates to the field of in-situ mechanical performance testing, in particular to an in-situ testing device for microscopic mechanical properties of materials under a tensile-shear composite loading mode. This device can be used independently as a test device for tensile and pure shear two kinds of material mechanical properties, and can also realize the composite load test of the two loads of tension and shear under different loading sequences, and can also perform high-frequency shear fatigue performance tests; The device can be placed under microscopic imaging equipment such as a metallographic microscope to observe in situ the microscopic morphology of the specimen during the tensile-shear composite load loading process, such as the generation, growth and expansion of microscopic cracks; it can realize load / Acquisition, conversion and control of displacement signals are used to accurately measure the mechanical properties of ma...

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Problems solved by technology

This test method results in two or more load modes that cannot be loaded independently or sequentially, so it is difficult to analyze different single load modes, and it is also impossible to analyze the mechanical properties and properties of materials and their products under the combined load of different stress combinations. Accurate assessment of degenerative injury mechanisms

[0005] The current in-situ nanomechanical testing technology has the following limitations: (1) Most in-situ nano-testing focuses on the simple in-situ testing of extremely small structures such as nanotubes, nanowires, and thin-film materials based on the principle of micro / nano-electromechanical systems. In terms of nano-tensile testing, there is a lack of in-depth research on cross-scale in-situ micro / nano-mechanical performance testing of macroscopic dimensions (thin film materials or three-dimensional specimens); (2) the current in-situ mechanical testing mainly relies on commercial in-situ nano The tensile tester and the nano-indentation tester perform in-situ nano-tensile testing and in-situ indentation testing respectively. Commercial testing equipment is expensive, the testing method is single, and it cannot provide mechanical testing of materials under multi-load composite mode; ( 3) When performing fatigue performance tests, the current in-situ fatigue testing machines can generally only provide low-cycle fatigue tests below 50HZ, which cannot reflect the mechanical properties of specimens and their products under actual fatigue conditions

Therefore, the traditional material testing machine loads the specimen until it is broken or sheared to obtain the mechanical parameters such as the tensile yield limit, tensile strength limit, shear yield limit, and shear strength limit of the material; and the traditional bending Most of the testing machines are aimed at large-scale macro-material-scale specimens, which do not involve in-situ observation under high-resolution microscopic imaging systems, and cannot carry out in-depth combination of composite loads, micro-mechanical behaviors of materials, and degenerative damage processes. Research

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