To increase the engineering applications of basalt fiber, the characteristics of the shear mechanical properties and the influence mechanisms of the fiber length ( Lf) and volume fraction ( Vf) for short basalt fiber reinforced epoxy resin polymer composites were investigated. The following results were obtained: (1) The first critical loads on all the shear load–displacement curves are close to the same value due to having the same interface bonding of the fiber–matrix; (2) the shear strength, deformation, and energy dissipation capacity all increase with increasing Vf; however, when Lf is 6 or 9 mm, these increases are slower, whereas when Lf is 3 mm, these values increase at an approximately constant rate; and (3) the shear elastic modulus of the samples reaches its maximum value when Lf is 3 mm and Vf is 25%; however, it increases more quickly when Lf is 6 or 9 mm. The failure mode of the samples with the larger Lf values is mainly debonding between the fiber and matrix; when Vf is high, the fibers can easily bundle, which reduces the adhesion between the fibers and matrix. In addition, the main failure mode of the 3-mm-long fiber samples is fiber pull-out; when Vf is high, the short fibers that are not pulled out significantly increase the deformation ability.

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In 2017, the pilot policy of green finance was initially officially implemented to govern the corporate environmental issue. Five provinces with different levels of development were selected to carry out pilot policies of green finance by being provided with credit support and low interest rate. This paper aims to study the effect of the implementation of green finance policies on local R&D. We look the pilot policy of green finance in 2017 as a natural experiment and use the DID method to regress the fixed effects of individuals and years with the R&D spending. We found that green finance policies could ease the constraints brought by the original local economic and political environment to enterprises. Another explanation may be that banks' financial support for enterprises improves the efficiency of R&D, reduces unnecessary R&D waste, and enables enterprises to continue to develop in the period of economic growth with less capital. In order to verify the validity of the model construction, we conducted the Hausman test to verify the validity of selecting the fixed effect, and conducted the parallel trend test to verify the accuracy of our 2017-2019 policy pilot time. Finally, we conducted two robust tests——placebo test to control the time and the PSM-DID. We all obtain the significant experimental results. Then, we puts forward policy suggestions based on the conclusions, which can be used as reference for future research and for the effect of the application of green finance policies in heavily polluting enterprises.

The tensile test of NOL ring composites with different interply hybrid ratio is simulated by finite element software. The relationship between the stress of Naval Ordnance Laboratory(NOL) ring and the volume fraction of UHMWPEF is linear when the matrix suffering from the equal loading, but tower suddenly appears at the point of 56.25% which is about the critical volume fraction. The critical volume fraction of hybrid NOL ring is figured out on the basis of the constant strain model. By contrast, the results of the Finite Element Method (FEM) and constant strain model have subtle differences. Tooth contact analysis can exactly predict the stress of the interply hybrid NOL ring and the critical volume fraction of GF in interply hybrid NOL ring which has lower breaking strain than UHMWPEF does.