tailieunhanh - Woven Fabric Engineering Part 14

Tham khảo tài liệu 'woven fabric engineering part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Effects of the Long-Time Immersion on the Mechanical Behaviour in Case of Some E-glass Resin Composite Materials 369 the shape of the curve obtained was approximately the same. It may be mentioned that the time of the flexural test was approximatelly equal to 10min. when the speed of loading was min. in case of the specimens reinforced only with the E-glass fibres. Before each mechanical test of a specimen the dimensions of the cross-section were accurately measured and then they were considered as input data in the software program of the machine. In case of the flexural testing the testing equipment allowed to record pairs of values force F and deflection v at midpoint of the specimens in form of files having up to 3000 recordings. The testing machine also gave the results of a statistical calculus for the set of the specimens tested. Experimental results recorded during the flexural tests were graphically drawn using F - v coordinates and finally the following quantities were computed - flexural modulus E of the composite material 1 l3 AF 48 I ÃŨ - flexural strength o of the composite material _ Mbz max Ơ W 1 2 where l 64 mm represents the span of the specimen between simple supports Fig. 3 Iz -moment of inertia Wz - elastic cross-section modulus Mbz max Fl 4 - maximum value of the bending moment. Formula used for the flexural modulus E is a good approximation because - - 16 where h represents the thickness of the specimen and one can neglect the effect of h the shearing force. 3. Results Water absorption The first moisture behaviour was analysed. The absorption data were shown in the figures 6 - 9 for all composite materials reinforced only with glass fibres. Important remarks are noted by analysing these results. Moisture absorption in composite materials depends on the resin used for matrix and type of the wet environment. The absorption process is a long-term process in case of the composite materials tested. E - glass Heliopol 8431 ATX and .