An Investigation On Photo-elasticity Model Of Internal-Combustion Engine By Laser Stereo-lithography Technology

Conventionally models in photoelastic analyses are made by casting general models with manufactured molds which is subject to manual or mechanical finishing, demanding high cost for molds and solutions to a number of problems with regard to casting processes and leading to prolonged experiment period. More seriously, some more sophisticated local features have to be ignored in producing complex photoelastic models when the conventional manufacturing method is applied, which causes distortion in the course of stress analyses.Nevertheless, the arrival of rapid prototyping (RP) technology makes rapid, automatic manufacturing of any complex mold possible and, similar to the conventional photoelastic material, i.e., epoxy resin, the major component in photosensitive resin, one of the prototyping materials for this new technology, is epoxy. Based on an analysis of the operating mechanism of stereolithography (SLA), this article presents a contrast between the features of photosensitive resin as a prototyping material and epoxy resin as conventional photoelastic material and puts forward an analysis of the theoretical feasibility in manufacturing photoelastic molds with the technology of stereolithography. Photosensitive resin material appropriate for photoelastic experiment are selected after an extensive process of careful selection and a general study is conducted on the photoelastic properties of the material which is followed with proposed improvement measures. Photoelastic experiment on the cross-pressed disc and pure bending of the beam testifies evident photoelastic behavior of the photoelastic mold made through SLA process together with the generation of a desired curve on thermo-optic effect. The research shows that, with optimized prototyping processes and post-processing technologies, photoelastic molds in line with experiment requirements can be manufactured by means of rapid prototyping.Cylinder head remains a crux in the researches in the intensity and reliability of internal combustion engines for the complexity in its structure and the stresses imposed on it. Photoelastic model is fabricated in this article on the basis of previous research findings and a stress freezing experiment conducted, and comparison shows the result of data processing and stress analysis after model slicing is basically identical to that of the finite element analysis (FEA). The research in this article indicates that the photosensitivity of photoelastic models made of photosensitive materials has much to do with prototyping materials and the model manufacturing processes and that optimized heat treatment process can significantly improve the photoelastic properties of the models and reduce the fringe value of the material. After completion of the stress freezing experiment applied to the cylinder cover, a process is identified in this article to manufacture photoelastic models through SLA which is to be subject to 3D stress field analysis. These leads to greatly shortened time for model manufacturing, rapidly realized experiment evaluation of the designed intensity of the new products and improve the competitive edge of photoelastic analyses. The technology proposed in this article is of advanced international standard and fills up the gap in the domestic technological domain.