23 August 2007 KKKJ 4363 PENGIRAAN BERANGKA Assignment #2 – 2D Finite Elements 23 August pm – pm

23 August 2007 Week 7 Page 2 Assignment #2 (adapted courtesy of ref. [1]) [1] Ahmad Kamal Ariffin & Muhammad Hafiz, Finite Elements in Engineering, KJ4363 Lecture Notes. An aluminium skin needs to be designed to carry some load on a high performance automobile. Suppose this load-carrying aluminium is supported at its corners (as shown in the figure below) and is required to withstand the load as shown in the figure. Assume body force may be neglected in comparison with the external forces. Thickness t = 5mm E = 70 GPa = 0.3

23 August 2007 Week 7 Page 3 Assignment #2 i)Assumming, as a start, 2 constant strain triangle elements are used, determine the critical von mises stress on the aluminium skin. ii)In the design, both structural requirement and weight saving need to be satisfied – hence, reliable critical stress information is important. Determine the minimum thickness of the aluminium skin, such that, no location on the plate is permanently deformed (assume the yield strength of aluminium is 300 MPa). Justify why you think your stress estimate is sufficiently accurate. iii)Plot the stress contour of the final aluminium skin design using the post-processing techniques in chapter 12 of our textbook (ref. [2]) [2] Chandrupatla & Belegundu, Introduction to Finite Elements in Engineering, Prentice-Hall 3 rd ed. (2002)

23 August 2007 Week 7 Page 4 Assignment #2 Note: 1.You will be assessed on the technical aspects (method, justification etc.). However, you will also be assessed on your communication skills (reporting & writing) 2.This assignment is due on the 30 th August 2007 at 1630 pm. Please STAMP your assignment from the general office before putting your report into the KJ4363 pigeon hole. Otherwise, it will be deemed late and be penalised. 3.SELAMAT BERUSAHA..