The test method usually adopts quasi-static analysis conditions, which can accurately calculate the TVMs of gear meshing pair. In practical application, due to the time-consuming, consumables and application limitations of the test equipment, it does not have the universality of wide application, but it is suitable for the basic data research and mathematical model verification of new product gear.

Based on the important evaluation parameter of stress intensity factor in crack propagation in fracture mechanics, Pandya et al. Measured this parameter to determine the change of gear tooth meshing stiffness when there is a crack in the spur gear system, built a spur gear meshing test platform, and used the traditional photoelastic technology to measure the possibility of gear meshing stiffness change under static load. At the same time, the prediction of lossless and damaged (cracked) gears is carried out, and the results are compared with those calculated by elastic strain energy method and total potential energy model.

Raghuwanshi et al. Introduced in detail the strain and stress measurement of gear pair under the condition of nondestructive or damaging (crack) by testing modal measurement method, laser displacement sensor technology, digital image correlation technology, strain gauge measurement technology and photoelastic technology through relevant research from 2015 to 2019, as shown in the figure The time-varying meshing stiffness of gear pair is calculated and evaluated by theoretical mathematical formula derivation, and the results are compared with those of analytical method and finite element method. Mbarek et al. Studied the meshing stiffness response and the time-frequency output analysis of the system through modal measurement method.

Xie et al. Proposed an improved matrix stiffness calculation method considering the structural coupling effect to make up for the difficulty of correctly calculating the time-varying meshing stiffness of the matrix stiffness analytical method under the double tooth pair meshing. The established stiffness model and load distribution ratio model were continuously modified in real time to improve the calculation accuracy. Finally, combined with the minimum potential energy method (MPEP), the time-varying meshing stiffness of single and double teeth is calculated and applied. Wang et al. Established the calculation of tooth stiffness and contact stiffness under the analytical method, coupled with the detailed finite element three-dimensional model considering the geometric effect of complex gear body (WEB effect, web hole effect, etc.), so as to calculate the time-varying stiffness effect of meshing gear in detail.