Polyplastics Co., Ltd. (president: Noboru Goto, head office: Minato-ku, Tokyo, Japan) has developed a parts life prediction scheme based on the visualization of strain distribution.
- 1. Background
- We provide our customers with total solution activities at all stages, from plasticization concept development to mass production. We are very proud of our product design technology, evaluation technology, and failure analysis technology. Customer demand for prediction technology, among others, is high, and we are focusing our energy on the development of prediction technology to ensure a higher degree of accuracy. Of the various prediction technology schemes, computer-aided engineering (CAE) is the most popular, and has already been applied to a wide range of fields. Although CAE is capable of accurately analyzing simple deformation behavior or stress behavior, it is difficult for this scheme to analyze operating areas consisting of different parts (especially when the relative motions of gears and link mechanisms, etc. are involved). As a solution to this problem, we developed a life prediction scheme using strain visualization technology on actual machines. We are introducing our scheme for predicting gear life, which is considered particularly difficult to forecast.
- 2. Overview
- Since the state of gear engagement keeps changing, it is difficult to predict their life with CAE. For this reason, gear life has been predicted under different conditions and based on the measurement results of standard gears.
Our newly developed life prediction scheme includes three engineering elements:
- (1) the visualization of strain distribution in an actual working environment;
- (2) the calculation of true stress from strain distribution; and
- (3) the use of our massive fatigue fracture life data.
- For strain measurement in (1), a digital image correlation method (DICM) is adopted. DICM is an approach that calculates strain from the distance of travel of the pattern applied to the sample surface through image processing. In the stress calculation in (2), a true stress-strain curve obtained from measurements, which takes deformation distribution into account, is used instead of a general stress-strain curve, which assumes that the entire test piece deforms uniformly. This ensures improved stress calculation accuracy and accurate life prediction. In (3), we calculate gear life from our massive fatigue fracture life data on a wide variety of materials. This scheme enables us to predict the life of gears made of any material, even if they have not been subjected to gear life evaluations.
- 3. Future Prospects
- The technology for calculating local stresses inherent in plastics is applicable to diverse life predictions and failure analyses, and we are planning to apply it to assist with the growing needs of our customers. We will also actively introduce this technology to our customers’ product design, production engineering, quality assurance, and other departments, and thereby promote more advanced solution activities.
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