The CAE- Driven Mechanical Design Process

Transcription

1 The CAE- Driven Mechanical Design Process A graduate- level mechanical engineering course inspired by Inspire Mark JAKIELA Hunter Professor of Mechanical Design Washington University in St. Louis

2 Syllabus + Calendar MEMS 5104: The CAE-Driven Mechanical Design Process! Lectures M. Jakiela (coord.) mjj@wustl.edu Office hours: T, Th and/or by appointment Teaching assistants Chiamaka Asinugo (coord.) ceasinugo@wustl.edu Wan-Jung Lin Wanjung.lin@gmail.com Course catalog description MEMS 5104: The CAE-Driven Mechanical Design Process An introduction to the use of computer-aided engineering (CAE) tools in the mechanical design process. Topics include integrating engineering analysis throughout the process, multidisciplinary optimization, and CAD systems directed toward new manufacturing processes. Students will be required to work with commercially-available and research software systems as they complete several small projects. Students should have basic experience with a CAD tool. Familiarity with optimization and the finite element method helpful. Grading Your grade is based on the following elements: Skill demo (5% each) 45% (Demos 1-9) Quizzes (5% each) 15% (Quizzes 1-3) Small project (10% each) 20% (Projects 1-2) Large project (20%) 20% (Project 3) Classroom time will be used for introducing assignments and online learning resources, as well as troubleshooting and proficiency demonstration. Textbooks (Required): Various online documentation and training materials. Will be introduced as needed. Schedule (subject to adjustments) Mondays 8/28 Intro and logistics Student version AltairUniversity account 1: Inspire Introduction 2: Inspire Interface 9/4 LABOR DAY NO Class Wednesdays 8/30 Install Hyperworks and Inspire 9/6 Geometry Create 3: Geometry Create & Simplify 3: Exercise: Create Geometry Skill Demo ( SD ) 1: Inspire Interface Updated 1/6/2004

3 Typical Skill Demo MEMS 5104: The CAE-Driven Mechanical Design Process Skill demo 3 (5%): Simplify/repair geometry Demonstrate the following steps for the instructor. Do all steps Deliverables: 1.! (0.5%) Complete 3:Exercise:SimplifyGeometry in Learn conceptual design with Inspire Show the instructor your completed model. 2.! (1%) In the manner shown in the screenshot saved on the Bb site, drill some number of holes through the rocker. Choose the number of holes, position/arrangement, and size so you are intuitively predicting how to minimize weight subject to yield strength. We will perform this analysis in a later skills demo. You must, therefore, save this file. 3.! (2%) Build a 3-sectioned part with two end pockets with all edges filleted, similar to the screen shot saved on the Bb site. 4.! (0.5%) Demonstrate to the instructor that you can remove all pockets and fillets with Simplify commands. After doing so, it should look like the other screen shot saved on the Bb site. 5.! (0.5%) Build an imprint on a face of this model. Demonstrate that Inspire can find and remove it using simplify commands. 6.! (0.5%) Build a small simple model that allows you to use the Patch command. Demonstrate for the instructor.

4 Product of Skill Demo

5 Product of Skill Demo

6 Product of Skill Demo

7 (Related) Skill Demo MEMS 5104: The CAE-Driven Mechanical Design Process Skill demo 6 (5%): Analysis Demonstrate the following steps for the instructor. Do all steps Deliverables: 1.! (3%) Complete 7:Analysis and results, and 7:Exercise analysis in Learn conceptual design with Inspire Show the instructor your completed model(s). 2.! (2%) In skill demo 3, you defeatured the rocker, and then drilled holes in it to guess a topology that might be feasible but be minimum mass. Do a stress analysis of this topology, comparing it to the Optistruct-optimized part that was shown in Step 9. This would be mass minimized subject to a von-mises based safety factor constraint of 1.2. Do both load cases and compare the mass and locations of 1.2 X von-mises stress.

8 Small Project 1 MEMS 5104: The CAE-Driven Mechanical Design Process Skill demo 1 (10%): Exploration of a stress amplifier Reproduce the described in section 7.2 Plate with a hole from the Inspire ebook, except use a different stress-concentration feature: you can choose either a (i) filleted flat bar in axial tension; or a (ii) notched flat bar in axial tension (See Norton machine elements book, 5 th edition figure C-9 and C-11) 1. Make a bar similar in overall size to the bar shown in section 7.2. Put the stress concentrating feature at the middle of the bar and choose values for r, d, and D that cause 2 <= Kt <= 3. Deliverables: 1.! (4%) Repeat all the steps that were done in section 7.2, exploring the influence of element size and faster versus accurate. 2.! (3%) Using the best values of element size and run speed, do a second study to try to shorten the length of the bar as much as possible. Do a series of runs, shortening the bar from both ends to try to minimize the number of elements in the model (element size and accuracy setting are held constant). Remove elements until the analysis results on the model begin to differ more than 5% from what is expected. Collect data and make a plot of run time versus number of elements in the model. 3.! (3%) Using this shortened bar length, try to minimize mass subject to a stress constraint of FS = 1.2 (i.e. Factor of Safety). (I.e. can we get rid of material in our stress-concentration test piece?) Note that it is likely that you will need to put a non-design-space boundary around the stress concentrating feature; you can try doing the optimization without it first. Present your results in a report document with format similar to that of section 7.2. (I.e. there will not be individual demos of results). 1 Also refer to example 8.1 in the same book.

9 Small Project 1 - Motivation

10 Small Project 1 Student Results

11 Small Project 2 MEMS 5104: The CAE-Driven Mechanical Design Process Small project 2 (10%): Topology optimization + casting simulation Produce a study similar to the one documented by Altair, in which a casting simulation using Click2Cast is integrated with a topology optimization done in Inspire 1. Choose a different structural part and determine its loading, boundary conditions, and appropriate casting technique. Some ideas 2 are: 1. Water well pump handle 2. Foot powered tire/sports-ball air pump lever 3. Vise-grip handle +Locking+Pliers/p72439 Although not structured in this way, you can see that there are three major steps documented in the Altair paper 1. Structural optimization using Inspire. This is documented in figures 1-8 and associated text. Note that figure 6 deals with choosing a draw type which depends on the casting technique chosen. 2. Using Click2Cast to check castability. (Figures 9, 10, 11, 12) And rechecking castability after some adjustments are made to the casting parameters. (Figures 13, 14, 15). 3. The following figures numbered as 8, 9, 10, 11, 21 should be renumbered as 16, 17, 18, 19, 20. These deal with performing additional casting analyses on the final design. Deliverables: 1. (4%) Repeat the three major steps identified above for you chosen part and casting technique. 2. (2%) Collect screen shots that serve the same purpose as figures 1 thru 20. The screenshots chosen and the number of screenshots might vary with the part and casting technique chosen. 3. (4%) Arrange the screen shots into a document with enough text explanation to understand the steps taken and what the results mean. An MSWord version of the Altair document will be provided on the course web site under the small project 2 link. 1 If instead you would like to use Click2Form on a part formed from a sheet, please see the instructor. 2 Or, choose a different part. Get approval from the instructor.

12 Small Project 2 - Motivation Topology Optimization & Casting Process Simulation using Altair Suite of Products Himanshu Singh, Prashant P. Hiremath, Subir Roy, John Brink, Andrew Stankovich; Altair Engineering Inc. Abstract Oftentimes, in the design of a casting, suboptimal structural concepts are developed which at the same time are not castable, requiring multiple and time-consuming design iterations. This paper describes a process to generate both structurally efficient and also castable parts, while reducing the overall design cycle time. The optimal structure is determined by topology optimization, reducing component mass while maintaining performance requirements. This step is followed by a design smoothing operation and then by a casting simulation to check for casting defects. To demonstrate this software driven product design and process validation, solidthinking Inspire is used to develop the concept design and Click2Cast for casting process validation. Both software are part of Altair s product suite and available through solidthinking and HyperWorks licensing. shown in Figure 1. A total force of 300 N is applied on the face of the arm while the lever ends are constrained, with one end being free to rotate. The part material and its details are provided in Table 1. Keywords Topology, Optimization, Manufacturibility Constraints, Casting Simulation, Inspire, Click2Cast, Weight Savings, Validation I.! INTRODUCTION During the design of components of a system, engineering s main focus is meeting structural product performance requirements. After a time-consuming manual design optimization process, if it is discovered that the part cannot be manufactured, the entire design cycle effort is wasted. Repeating the whole process is a waste of time, money and effort. Topology optimization is a proven approach for developing structurally efficient parts in a fraction of the typical design cycle time. To ensure manufacturability, casting simulation has become a powerful tool for analyzing the mold filling, solidification and the cooling process. It guides the design from casting defects like air entrapment, porosity, cold shots etc. For the case study reported in this paper, a robot arm has been considered. Concept level optimization is carried out using solidthinking Inspire with real field loads & manufacturing constraints. Several optimizations have been performed considering different manufacturing options with a final design selected meeting all the performance targets. This final design is analyzed with Click2Cast to investigate the casting process and any potential defects. II.! DESIGN OPTIMIZATION The existing design of the robot arm in an assembled condition with all the loads and boundary conditions are Figure'1:'Existing'design'with'applied'loads'and' boundary'condition' Table 1: Material data Young s Yield Part Material Poisson s Density Modulus Name Ratio (t/mm 3 Strength Mass ) (MPa) (MPa) (kgs) Aluminum E (A380) Linear static analysis is performed in Altair s Inspire software. The model is analyzed for static equilibrium to find the stresses and deflections (Figure 2).

13 Small Project 2 Student Results

14 Large Project MEMS 5104: The CAE-Driven Mechanical Design Process Large project (20%): Design your own project By now you have gained a good introduction to Inspire and the Hyperworks platform. For this final ( large ) project, you need to learn one more topic and apply it to a projectlevel problem of your own choosing. Please choose one of the following 5 topic areas 1. Associated learning modules for programs you must use in your study are included: 1.! 3D surface modeling. Learn 3D modeling with Evolve. You must use Evolve and Click2Form. 2.! Multibody FEM simulation. Intro to SimLab. You must use SimLab and Optistruct. 3.! Multibody dynamic simulation. Learn multibody simulation using Motionview and Motionsolve. You must use Motionview and Motionsolve. 4.! Composite analysis and optimization. Composite analysis with Hyperworks, and Learn composite optimization with Optistruct. You must analyze and optimize a composite layup using Optistruct. 5.! Thermal analysis. Thermal analysis with Optistruct. You must use Optistruct. 6.! Linear dynamics. Linear dynamics with Optistruct. You must use Optistruct. The deliverables will be short sections in a final report. Deliverables: 1.! (3%) Chosen problem. Briefly describe the problem you have chosen. Explain how it falls under one of the six topic areas described above. It is strongly recommended that you discuss this choice with the instructor before committing to it. 2.! (6%) Extension of the instruction. Explain how you will modify/extend an example or approach from one of the instruction modules 2. 3.! (4%) Model preparation. Explain how you prepared the model that is used for analysis and optimization. 4.! (4%) Results. Display, summarize, and explain. 5.! (3%) Discussion/conclusions. 6.! References (if any) 1 Other Hyperworks topics, and associated programs, may be considered pending instructor approval. 2 Recall this is how the skill demos were devised.

15 Large Project Student Results

16 V 2 Changes and Revisions Pick up the pace Increase coach/student ratio Compare several tools Outputs Interfaces