本文旨在通过实验阐明乙烯-醋酸乙烯酯共聚物(EVA)的动态破碎机理和性能,分析密度和厚度对其在动态冲击载荷下的力学行为和能量吸收性能的影响。因此,对不同密度和厚度的EVA泡沫进行了一系列动态压缩试验。冲击能量为66.64J时,对于密度为150kg/m3的泡沫,最大接触力,最大位移,最大应变,吸收的能量,比能量吸收(SEA)增加了20±2%,-38.5±2%,-38.5±2%,4±2%,和105±2%,分别,与密度为70kg/m3的泡沫相比。不同厚度样品的吸收能量与冲击能量之比几乎相等。试样密度对能量吸收效率没有影响,对SEA影响较大。同时,当冲击能量与厚度比为1680J/m时,与厚度为30毫米的泡沫相比,最大接触力,最大位移,最大应变,吸收的能量,对于厚度为60mm的泡沫,SEA增加了28.5±2%,211.3±2%,56.6±2%,100.8±2%,和0.4±0.5%,分别。冲击能量为66.64J时,与厚度为30毫米的泡沫相比,最大接触力,最大位移,最大污点,吸收的能量,对于厚度为60毫米的泡沫,SEA增加了-42.5±2%,163.5±2%,31.7±2%,4.1±2%,和4.1±2%,分别。两种不同厚度EVA试样的SEA几乎相等,约2.8J/g。不同厚度试样的吸收能量与冲击能量之比几乎相等,均为72%。试样厚度对能量吸收效率没有影响,对最大接触力影响较大。在冲击能量范围内,厚度,和密度研究,吸收能量和SEA不受EVA试样厚度的影响,由冲击能量决定。密度对吸收的能量没有显著影响,但对SEA有较大影响。然而,对于EVA泡沫,密度越大,质量越大,成本越高。考虑到轻量化和成本因素,在安全范围内优化缓冲设计时,我们可以选择密度和厚度较小的EVA泡沫。
This paper aimed to experimentally clarify the dynamic crushing mechanism and performance of ethylene vinyl acetate copolymer (EVA) and analyze the influence of density and thickness on its mechanical behavior and energy absorption properties under dynamic impact loadings. Hence, a series of dynamic compression tests were carried out on EVA foams with different densities and thicknesses. When the impact energy is 66.64 J, for foam with a density of 150 kg/m3, the maximum contact force, maximum displacement, maximum strain, absorbed energy, and specific energy absorption (
SEA) increased by 20 ± 2%, -38.5 ± 2%, -38.5 ± 2%, 4 ± 2%, and 105 ± 2%, respectively, compared to foam with a density of 70 kg/m3. The ratios of absorbed energy to impact energy for different thickness specimens are almost equal. The specimen density has no effect on the efficiency of energy absorption and has a greater effect on the
SEA. Meanwhile, when the impact energy-to-thickness ratio is 1680 J/m, compared to foam with a thickness of 30 mm, the maximum contact force, maximum displacement, maximum strain, absorbed energy, and SEA for foam with a thickness of 60 mm increased by 28.5 ± 2%, 211.3 ± 2%, 56.6 ± 2%, 100.8 ± 2%, and 0.4 ± 0.5%, respectively. When the impact energy is 66.64 J, compared to foam with a thickness of 30 mm, the maximum contact force, maximum displacement, maximum stain, absorbed energy, and
SEA for foam with a thickness of 60 mm increased by -42.5 ± 2%, 163.5 ± 2%, 31.7 ± 2%, 4.1 ± 2%, and 4.1 ± 2%, respectively. The
SEA of two different-thickness EVA specimens is almost equal, about 2.8 J/g. The ratios of absorbed energy to impact energy for different thickness specimens are almost equal, both at 72%. The specimen thickness has no effect on the efficiency of energy absorption and has a greater effect on the maximum contact force. In the range of impact energy, thickness, and density studied, the absorbed energy and SEA are not affected by the thickness of EVA specimens and are determined by the impact energy. The density has no significant effect on the absorbed energy but has a greater effect on the
SEA. However, for EVA foams, the greater the density, the greater the mass, and the higher the cost. Taking into account lightweight and cost factors, when optimizing cushioning design within a safe range, we can choose EVA foams with a smaller density and thickness.