Failure Mechanism of the Fixed Rigid Ejection Mechanism in Firearms

doi:10.12382/bgxb.2022.0090

Abstract

Abstract: Thisstudy employs the failure mode and effect analysis (FMEA) method to study the failure mechanism and mathematical modelling of fixed rigid ejection mechanism, and to obtain failure modes and influencing factors. The two main controlling factors are the ejecting speed and the relative position of the ejector and ejection opening. Adynamics model is developed and the performance parameters are obtained. The failure criteria are acquired based on failure modes. The failure boundary analysis and experimental verification of the main factors are carried out using the structural parameters of a small-caliber automatic rifle as an example. Both theoretical calculations and experimental results indicate that higher ejecting speed leads to higher reliability. Besides, a significant bidirectional boundary effect is found in ejection opening displacement,demonstrated as the under-constrained(over-constrained) effect of the ejection opening on the cartridge case and changing position of the impact point. The direct causes of case jamming failure are the inward rebound of the cartridge case and secondary impacts.

Key words: fixedrigidejectionmechanism, failuremechanism, failuremodeandeffectsanalysis, failurecriteria, boundaryanalysis

CLC Number:

TJ22

FANG Yichuan, WANG Yongjuan, SHA Jinlong, NI Xiaoyang, LU Xingyu. Failure Mechanism of the Fixed Rigid Ejection Mechanism in Firearms[J]. Acta Armamentarii, 2022, 43(9): 2252-2262.

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