Abstract
This paper presents an experimental study of the protective properties of warp-knitted spacer fabrics developed for protecting the human body on impact. A drop-weight impact tester was used to test the fabrics in a hemispherical form to simulate the use of impact protectors in real life. The study consists of two parts. The first part, presented in the current paper, focuses on the impact behavior of a typical spacer fabric impacted at different levels of energy. The analysis includes the impact process and the energy absorption and force attenuation properties of the spacer fabric. Frequency domain analysis is also used, to identify the different deformation and damage modes of the fabric under various levels of impact energy. The results show that the impact behavior of the fabric under impact in the hemispherical form is different from that in the planar form. The results also indicate that the curvature of the fabric can reduce energy absorption during the impact process and therefore reduce the force attenuation properties of the spacer fabric. This study provides a better understanding of the protective properties of spacer fabrics. The effect of fabric structural parameters and lamination on the protective properties of spacer fabrics under impact will be presented in Part II.
Over the past few decades a wide range of personnel protective equipment (PPE) has been developed to protect wearers from various types of risks or hazards to their health and safety.1–7 Impact protectors, which are the most commonly used PPE, are normally manufactured to include energy-absorbing material in the form of pads.8,9 They are integrated or inserted into protective clothing or equipment specially designed for protecting the human body from impact, blows or falls. A number of different types of impact protectors are on the market for protecting different areas of the body in a variety of circumstances.1–4
Conclusions
A typical warp-knitted spacer fabric developed for human body protection against impact was tested in the hemispherical form at different levels of impact energy. Its impact resistance, energy absorption and force attenuation properties were investigated in the light of the experimental results. The frequency domain analysis with HHT method was also used to analyze its different deformation and damage modes. According to the experimental results and analysis, the following conclusions can be drawn:
1. The boundary condition determines the impact response of the spacer fabric. The plateau stage of the spacer fabric under impact in the hemispherical form is not clearly observed due to the change of the contact area of the fabric during the impact process and different deformation stages of spacer yarns under similar displacement of the striker.
