# Design of a Novel Linear Shaped Charge and Factors Influencing its Penetration Performance
## 1 Introduction  
In some emergencies, such as suspect capture, emergency rescue, and fire rescue, the first question is how to quickly open an emergency passage. One of the most effective ways is using a metal jet formed by a linear shaped charge (LSC), which can break up obstacles and reduce collateral damage.  
Since the pioneering work of [PERSON], the steady state theory of [PERSON] and the unsteady state theory of PER ([PERSON], [PERSON], and [PERSON]) have been widely used in studies of shaped charges. Most of the researches in this field are focused on conical shaped charges (CSCs) and there have been few publications about LSCs [1; 2]. [PERSON] [3] proposed an unsteady theory of jet formation for end-initiated LSCs, and confirmed that the theory agreed well with experimental results in the case of a charge with constant thickness. With the development of numerical simulation technology, the mechanism of LSC jet formation has been further analyzed and researched. [PERSON] established a steady-state analytical equation of motion of a LSC's liner based on the modification of the original [PERSON] theory [4] and showed that compared with numerical simulation results created with Autodyn software, this analytical equation exhibited favorable results in a limited range. [PERSON] also proposed a theoretical model to predict the behavior of an explosively driven flyer, and calculated the jet tip velocity based on the formation of an arc in the liner. Some researchers studied the characteristics of the-liner collapse line using a typical jet flight pattern of LSC [5; 6; 7; 8; 9]. For the simulation method, smoothed particle hydrodynamics (SPH) was used to investigate the formation process of a linear-shaped charge jet [10; 11; 12]. [PERSON] conducted a standoff test of a LSC that provided significant information about determining the optimal standoff distance and allowed the design of effective cutting plans for use with LSCs [13; 14]. [PERSON] experimentally determined the effects of a mass of explosive, liner material and standoff distance on the penetration depth of the LSCs [15; 16].  
The shape of a shaped charge liner has great influence on the formation of metal jet and its penetration performance into a target. The researchers mainly focused on LSCs with a single-apex-angle liner. This paper describes an experiment using bi-apex-angle linear shaped charges (BLSCs) for effective penetration. A typical BLSC is shown in Figure 1. The greatest difference distinguishing a BLSC from the traditional LSC is a small-apex-angle liner that is added in an ordinary LSC liner. In this paper, the penetration performance of a BLSC is tested by the depth-of-penetration (DOP) test, and the results show that its penetration depth is 29.72% better than that of an ordinary LSC. The penetration performance of the BLSC and LSC is then investigated by Autodyn-2D. Based on the validated numerical approach and models, we comprehensively discussed the influences of liner thickness, explosive type, a combination of small and large apex angles, and a ratio of small to all apex angle liners on the penetration performance of BLSCs. The present study provides a guidance and reference for the structural design of a BLSC.