A method of eliminating the influence of air layer in the holding device of shtb test

Abstract

The invention belongs to the field of impact dynamics, and in particular relates to a method for eliminating the influence of an air layer in a SHTB test clamping device. It includes the following steps: Step (1): Considering that there is an air layer between the SHTB test clamping device and the test specimen, the experimental model is simplified based on the assumption of uniformity and one-dimensional stress; Step (2): The clamping section containing the air layer The interface before and after the hollow air layer is defined as the interface of different medium layers; Step (3): By analyzing the transmission and reflection of the stress wave in the rod in different medium layers in the experiment, the change of the stress pulse under different medium layers is obtained; Step (4) : The incident wave, transmitted wave and reflected wave signals obtained in the experiment are corrected according to the change of the undershoot of the stress pulse at different medium layers in step 3. The invention considers that the SHTB experimental device contains an air layer, uses the transmission and reflection analysis of stress waves in different medium layers, and corrects the experimental data by eliminating the influence of the air layer, thereby improving the accuracy of the experimental data of the SHTB experiment.

Description

technical field [0001] The invention belongs to the field of impact dynamics, and in particular relates to a method for eliminating the influence of an air layer in a SHTB test clamping device. Background technique [0002] With the development of society and economy, more and more major projects that benefit the country and the people have been built. These structural projects are often tall and complex. While carrying normal design loads, they must also have the ability to withstand extreme environmental effects or some accidental accidents, such as earthquakes, fires, explosions, impacts, etc. This requires us to have a more comprehensive understanding of the mechanical properties, especially the dynamic mechanical properties, of these structural engineering materials (such as metals, concrete, rocks, etc.). As an effective means of studying the dynamic mechanical properties of materials, the Hopkinson bar test system has been widely used in recent decades and has become...

AI Technical Summary

Problems solved by technology

The separate Hopkinson tie rod experimental device has also been continuously improved in the development of experimental technology. The connection between the sample and the loading rod in the current SHTB is mainly a threaded connection, which belongs to the fixed connection method, and the complexity of the connection form, the test piece The length and the length of the thread of the inner ring of the loading rod are often inconsistent, which will cause gaps between the two ends of the specimen and the rod at the joint, and an air layer will remain, and the stress pulse signal will have large transmission and reflection at the interface of the air layer, which will cause the test error

[0004] The existing SHTB experimental data is processed based on the one-dimensional stress assumption and the uniformity assumption, and the original measurement test data is processed by the two-wave method or the three-wave method. Gap, thus ignoring the difference between the original measurement test data and the real stress state experienced by the test specimen, which makes the dynamic mechanical properties obtained by the separated Hopkinson tie rod test material deviate from the actual

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