tailieunhanh - Heat Transfer Engineering Applications Part 6

Tham khảo tài liệu 'heat transfer engineering applications part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Experimental and Numerical Evaluation of Thermal Performance of Steered Fibre Composite Laminates 139 For variable-stiffness panels a family of curves corresponding to various values of T1 from 0 to 90 in increments of 15 is plotted in Figure 12. The lowest normalized value of stressresultant is and is obtained for a variable stiffness configuration of To 85 and T1 0 with normalized longitudinal deflection value of about . This value is 68 lower than the lowest value of obtained with a straight-fiber configuration but with 12 increase of normalized longitudinal deformation. Most variable stiffness panels with To 0 and T1 in the range of 0 to 45 have a higher stress resultant than the corresponding straight-fiber configurations. Normalized longitudinal deformation Fig. 12. Normalized longitudinal stress resultant for 0 To T1 90 Tg Ti s 6. Thermal testing of variable stiffness laminates The thermal-structural responses of two variable stiffness panels and a third cross-ply panel are evaluated under thermal loads. A brief description of the variable stiffness panels and their fiber orientation angles is given along with an overview of the thermal test setup and instrumentation. Results of these tests are presented and discussed and include measured thermal strains and calculated coefficients of thermal expansion. Fiber tow path definition The layups of the three composite panels tested in this study are described herein. The two variable stiffness panel layups are 45 04 s where the steered fiber orientation angle 0 varies linearly from 60 on the panel axial centerline to 30 near the panel vertical edges cm away. The curvilinear tow paths that the fiber placement machine followed during fabrication of these variable stiffness panels are shown in Figure 13. One panel has all 24 tows placed during fabrication. This results in significant tow overlaps and thickness buildups on one side of the panel and therefore it is designated as .