Performance characteristics of Hopkinson’s set-up pneumatic launcher

Kamil Sobczyk,Ryszard Rekucki,Leopold Kruszka,Ryszard Chmielewski

doi:10.14311/ap.2021.61.0552

Kamil Sobczyk, Ryszard Rekucki + Show 2 more

Open Access

https://doi.org/10.14311/ap.2021.61.0552

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Journal: Acta Polytechnica	Publication Date: Aug 31, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Military University of Technology in Warsaw

Abstract

The paper presents a performance characteristics of a pneumatic launcher, which is an important element of the split Hopkinson bar set-up (SHPB) at the Department of Military Engineering and Infrastructure (the Military University of Technology in Warsaw) for the purpose of dynamic strength tests of construction materials. The process of experimental calibration of the launcher for selected loading bar-projectiles is shown. Two types of compression during direct impact tests were also used simultaneously to investigate the behaviour of metallic samples with the use of this launcher as well as the Hopkinson measuring bar: the first — a short cylindrical sample, including a miniature (small diameter) sample, and the second — a long cylindrical sample (Taylor test). The relationships describing the stress and strain state as a function of strain rate for the first type of the experiment and engineering empirical formulas for the second type of the research were given.

Highlights

The beginnings of the development of gas launchers are related to a military technology
The stationary pneumatic launcher, which is an element of the SHPB, intended to test the behaviour of material samples subjected to dynamic loads, does not meet the statutory definitions of “firearms”, “gun” and “pneumatic weapons” [22]
From the point of view of objectivity of dynamic tests, it is necessary to conduct preliminary tests to validate the pneumatic launcher, a so-called calibration procedure, before a series of physical experiments to obtain empirical relationships between the working pressure and the impact velocity for the geometric parameters of the bar-projectile used in further tests, which characterize the performance of this launcher

Summary

Introduction

The beginnings of the development of gas launchers are related to a military technology. The stationary pneumatic launcher, which is an element of the SHPB, intended to test the behaviour of material samples subjected to dynamic (shock) loads, does not meet the statutory definitions of “firearms”, “gun” and “pneumatic weapons” [22] This means that pursuant to the Act of June 13, 2019 on the performance of economic activity in the field of production and trade in explosives, weapons, ammunition, and products and technology for military or police purposes [23] it is not considered a weapon. From the point of view of objectivity of dynamic tests, it is necessary to conduct preliminary tests to validate the pneumatic launcher, a so-called calibration procedure, before a series of physical experiments to obtain empirical relationships between the working pressure and the impact velocity for the geometric parameters of the bar-projectile used in further tests, which characterize the performance of this launcher This is especially important during various schemes for material impact tests with the use of the pneumatic launcher. The subject of this work is devoted to these issues

Characteristics of the pneumatic launcher of the SHPB stand

Pneumatic launcher calibration procedure

Impact tests with the use of an SHPB pneumatic launcher

Conclusions