Ndukwe Christopher O, Ezurike Benjamin O, Okpala Paul C
Department of Mechanical Engineering, Madonna University, Nigeria.
Department of Mechanical/Mechatronics Engineering, Alex Ekwueme Federal University, Ndufu-Alike, Nigeria.
Heliyon. 2021 May 18;7(5):e06887. doi: 10.1016/j.heliyon.2021.e06887. eCollection 2021 May.
The investigation and comparative analysis of Chopped Strand Mat Glass Fibre Reinforced Polyester (CSMGFRP) composite laminates was conducted. The laminate samples for the experiment were first exposed to diverse X-rays intensity rates at 6 mAs interval before test under cryogenic temperature. The generated values for tensile properties like young's modulus, strength, force, energy and elongation values were all measured and noted. The tensile modulus presented 43.8% decrease at the first 12 mAs exposure before it started increasing in the order of 30.3%, 6.3% and 12.3% respectively. Also, a science laboratory (SciLab) numerical evaluation of the material's tensile young's modulus was carried out and the obtained values compared with the experimental result to ascertain the level of relationship between the two approaches. It was observed that all the tested tensile properties were not consistent in the line of material strength depreciation values, apart from tensile young's modulus. The latter is consistent, but when considered with numerical model; their values became inconsistent like the former. However, when Analysis of Variance (ANOVA) for both approaches (experimental and SciLab numerical evaluations) were checked using t-test for pair comparisons, the data sets produced a computed t-value of 4.51. The obtained t-value and the critical t-value of 2.57 for 5% level of significance and 5-degree of freedom were compared, and it was noticed that the obtained t-value was higher than the critical t-value which indicated that the result was significant at the 5% level. Thus the null hypothesis is rejected which suggests that both approaches were relevant to tensile properties investigation at cryogenic temperature.
对短切毡玻璃纤维增强聚酯（CSMGFRP）复合层压板进行了调查和对比分析。实验用的层压板样品在低温测试前，首先以6毫安秒的间隔暴露于不同的X射线强度率下。测量并记录了拉伸性能产生的值，如杨氏模量、强度、力、能量和伸长率值。在最初暴露于12毫安秒时，拉伸模量下降了43.8%，之后开始分别以30.3%、6.3%和12.3%的顺序增加。此外，还对该材料的拉伸杨氏模量进行了科学实验室（SciLab）数值评估，并将获得的值与实验结果进行比较，以确定两种方法之间的关系程度。观察到，除了拉伸杨氏模量外，所有测试的拉伸性能在材料强度折旧值方面并不一致。后者是一致的，但与数值模型一起考虑时；它们的值变得像前者一样不一致。然而，当使用配对比较的t检验检查两种方法（实验和SciLab数值评估）的方差分析（ANOVA）时，数据集产生的计算t值为4.51。将获得的t值与5%显著性水平和5自由度的临界t值2.57进行比较，发现获得的t值高于临界t值，这表明结果在5%水平上是显著的。因此，原假设被拒绝，这表明两种方法都与低温下的拉伸性能研究相关。
