Photoelasticity using liquid crystal display of laptop computer as light source

Abstract

This paper presents photoelasticity using liquid crystal display (LCD) of laptop computer as light source for engineering education. First, angle of the polarizing axis in LCD was investigated using analyzer. Second, the photoelastic experiments were performed to acrylic rod using an LCD and commercially available educational photoelasticity device, respectively. As the results, the isochromatic line fringe pattern obtained using LCD was seen as well as that of the commercially available device. The photoleastic sensitivity values measured from these fringe patterns were good agreement. Therefore, the photoelasticity using LCD can be ensured a certain level of quantitativity. Moreover, the photoelastic experiments using polarizing lights of red (R), green (G) and blue (B) primary colors of LCD were performed. Optical spectrums of the lights were also measured. As the results, it was confirmed that colors of the isochromatic line fringe patterns correspond directly to the each spectrums. In addition, it was shown that measurement of photoelastic constant and stress analysis can be performed on the basis of single fringe method using the polarizing light of G primary color. For using this method, it is important that the characteristics of polarizing lights of R, G and B primary colors is understood. Finally, the photolesticiy experiment using LCD was lectured to corporate engineers in open lecture of National Institute of Technology, Numazu College. The questionnaire results showed that the photolesticity experiment was an effectual method for mechanics of materials education since the corporate engineers admired for easy investigating a stress concentration. Photoelasticity using LCD denotes handy method which can be learned fundamental photoelasticity and mechanics of materials including association with characteristics of the lights because of LCD is given variety of polarizing lights.