Study On Tensile Fracture Morphology Of Nondirectional PMMA Based On Fractal Theory

In recent years,aeronautical perspex is widely used in aircraft,accidents caused by aeronautical perspex damage have occurred.In order to avoid such accidents happen frequently,it is important to investigate the cause of aeronautical perspex failure,but the aeronautical perspex failure analysis are mainly qualitative analysis of fracture surface morphology in currently,and the systemic,regular,cognizable diagnostic basis rule with conditions is not complete,so finding a suitable quantitative analysis method of PMMA fracture and exploring the relationship that between fracture morphology and fracture condition has great significant for PMMA failure analysis.Firstly,stereoscopic microscopy and scanning electron microscopy were used to observe the fracture morphology of PMMA(YB-2),by establishing the fitting curves of the fracture morphology parameters and the tensile conditions,the tensile fracture morphology of PMMA with thicknesses of 2.5 and 5 mm respectively has the same rule: when the tensile rate is constant,the size of the mirror regions and mist regions increase with the increase of the tensile temperature,and the surface roughness of the mist regions decreases with the increase of the tensile temperature,when the tensile temperature is constant,the size of the mirror regions and the mist regions decrease with the increase of the tensile rate,and the surface roughness of the mist regions increases with the increase of the tensile rate.Secondly,the fracture morphology was described by fractal theory,it shows that the mist regions and hackle regions of PMMA has fractal features,and the mist regions SEM images belongs to random fractal graphics.In order to explore the relationship between fractal dimension and tensile conditions,the curve fitting of the mist regions fractal dimension and tensile condition was established.The results show that the mist regions fractal dimension of PMMA increases with the increase of tensile temperature,and decreases with the increase of tensile rate.At last,in order to explore the relationship between morphological parameters and fractal dimension,the curve fitting of the fractured mist regions morphological parameters and fractal dimension was carried out.The results show that at the fitting curve of the mist region size and its fractal dimension is directly,the fitting curve of the mist region surface roughness and its fractal dimension is inversely,but there are differences in the fitted linear relationship between different tensile conditions and sample thickness.