TMA 02 This module requires all assignments to be submitted electronically. To submit an assignment, please follow the link(s) from your StudentHome page to the online TMA/EMA service. There are restrictions on the size and format of any files you submit for TMA 02 via the online TMA/EMA service. The maximum file size permitted for TMA 02 is 10 MB. Guidance on reducing the size of images is available on the Resources page of the module website. You can only submit .doc, .docx, .xls, .xlsx or .rtf documents, or zipped files containing only .doc, .docx, .xls, .xlsx or .rtf documents. If you foresee any difficulty with submitting your assignment on time, you should contact your tutor well in advance of the cut-off date. For further information about policy, procedure and general submission of assignments please refer to the Assessment Policies, which can also be accessed via your StudentHome page. Note also the University's policy on plagiarism in the Assessment Policies. TMA advice This assignment covers Blocks 1 and 2. It consists of just one question or activity comprising 100% of the marks available for this assignment. Read through the question and all the accompanying notes, particularly the Further guidance on your TMA section, before starting work. Make sure you read the question carefully. Look for key words that will clarify how you are to approach the answer. For this assignment a report is required of the form expected for an engineering analysis project - more detailed guidance as to the contents is given in the question instructions below. Other general advice is available in Skills for OU Study: Assignments. It is important to recognise the TMA as more than just part of the means by which the University awards your module grade. It is a vital part of your learning process, which is why you receive feedback on it. You should contact your tutor in advance to discuss any aspect of the TMA about which you are unsure, and then again after you receive your script back, if there is any aspect of the marking that you would like to follow up. Question 1 This question carries 100% of the marks for this assignment. A simplified three-dimensional approximation of an aluminium bicycle frame and schematic dimensions are given in Figure 1. Your objectives are to model the frame and conduct analyses to investigate its strength and stiffness under two given load conditions, and write an engineering style report on your analysis and interpretation of the results. This report is actually the TMA that will be marked. 420 7 14 LIO 50 LII www L9 1.2 SEAT PEDAL CRANK 17 60 Figure 1. A simplified three-dimensional bicycle frame Table 1 Material Type Material Property. Young's Modulus (E) Poisson's Ratio Density Yield Stress Outer Diameter Thickness Aluminium Al (6061-T6) Value 75 GPa 0.30 2725 kg m-3 276 MPa 26 mm 2 mm From the geometric information given in Figure 1 and the material data in Table 1, construct the base ANSYS model. The joints labelled 1, 2, 3 etc. are effectively the key points KP1, KP2, KP3 etc. for establishing the geometry of the frame with reference to the X,Y,Z axis set. Some of the coordinate values you'll have to work out from the dimensions. The frame tube members or link lengths are labelled L1, L2, L3 etc. When constructing the model, use SI units and adhere to the key-point and line numbering scheme given in Figure 1. Initially, the cross-sectional dimensions to be used for the hollow aluminium tube are those given in Table 1. For meshing the model, use an appropriate PIPE element, e.g. PIPE288 elements. Although the bike is under dynamic loads, we consider only two static cases in this analysis: Load Case 1: Vertical Bending Test Load case 1 is a 760 N vertically oriented down load (-Y) at the seat position (KP3) and a total vertically oriented down load (-Y) of 500 N split equally at the pedal crank positions (KP7 and KP8). To account for some of the dynamic effects in this static analysis, multiply all the loads by a factor of 2. Use a ball-joint boundary condition for the front dropout (KP1) and a sliding boundary condition for the rear dropouts (KP5 and KP6). You should carefully consider how these conditions are modelled as constraints in displacement and/or rotation in each boundary. Load Case 2: Horizontal Impact Test Load case 2 is a horizontal (+X) load of 700 N applied to the front dropout (KP1). The rear dropouts (KP5 and KP6) are fully restrained in all translations. Multiply load by a factor of 2. Required outputs from the analysis The outputs required for these two load cases are: ● ● Maximum von Mises (SEQV) stress Maximum x-displacement Maximum y-displacement Plots of the von Mises and axial stresses Bending moment and shear force diagrams. Some of this data may be extracted directly in ANSYS. Other items may need to be obtained using element table data. To do this, you should read about the element of your choice in the ANSYS manual, in particular, input and output options. An example of an element table extraction for axial stresses at angle 0 from the PIPE288 element is as follows: ETABLE,AXIIO, SMISC,31 ETABLE, AXIJO, SMISC, 36 PLLS,AXII0, AXIJO AXII0 and AXIJO are names you assign to the required data SMISC 31 and 36 are the required data items for the I and J nodes, respectively PLLS displays element table data as contoured areas along elements. Your report should be written so that a person reasonably familiar with FEA (but not necessarily with ANSYS) will understand it. Further analysis When you are happy that your model is producing sensible results, use it to do some design and optimisation. Do this by carrying out further analysis runs to try different design options using your engineering judgement and your ANSYS model. Use Load Case 1 for this activity and suggest or try modifications to your model to make the design more efficient in terms of the loads and stresses carried by the members - i.e. are some of them overloaded or could they even be reduced in size? Keep the overall design the same as regards the number and layout of the members but create new models with different diameters and thicknesses as you think fit. Based on your initial analysis, which structural members look like they may be too large or too small, with respect to their outer diameter? Modify these and compare the effects on resulting stresses. For design limits and choices assume that the outer diameter can be changed in steps of 1.0 mm, leave the thickness at 2 mm and do not allow any displacement (Ux, Uy, U₂) greater than 0.8 mm. The TMA report Your TMA should be an engineering type report on your analysis and investigations. Ten pages should suffice to include a verification section, explicit statements of all assumptions, log or input files (in an appendix), and a compare and contrast (discussion) section. Your report should also include some displacement values at key points, especially the highest ones and plots from the relevant element tables including: axial stress shear force and bending moment diagrams equivalent (von Mises) stress. Further guidance on your TMA The following table gives guidance on what you need to think about and include in your TMA, and the breakdown of the marks for the various aspects of the analysis: Aspect Loading conditions Boundary conditions Assumptions Elements Results Verification Guidance Ensure that the loads have been applied correctly to take provisional account of dynamic factors as suggested. Think about what the loading conditions might represent in reality. Can these be considered as worst cases? We are looking for appropriate choice and applications and any comments on what the boundary conditions might represent. Assumptions could include discussion of the load conditions in a bit more depth. Are there any other loads that might need to be included, separately or together in your opinion, in designing a bike frame like this? Have you made any assumptions in modelling the structural joints in the frame? The choice of elements is given, but are they appropriate and would you try any other types if you were given a free hand? In particular, advantages and disadvantages of using shells or solids instead of pipes. Note that there are two lots of results required; the initial main results being the maximum von Mises stress values, maximum x and y displacements. Also required are direct stresses, shear force and bending moment diagrams. What are the results and what do they mean in relation to the applied loads? What about long-term effects such as fatigue life etc.? We'd expect to see some verification calculations and checks, for example ballpark types of calculations on member loads and stresses. Marks 5 5 10 10 20 20/n

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tma 02 this module requires all assignments to be submitted electronic

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TMA 02 This module requires all assignments to be submitted electronically. To submit an assignment, please follow the link(s) from your StudentHome page to the online TMA/EMA service. There are restrictions on the size and format of any files you submit for TMA 02 via the online TMA/EMA service. The maximum file size