The  CAE-­‐Driven  Mechanical  Design  Process

A  graduate-­‐level  mechanical  engineering  course  inspired  by  Inspire

Mark  JAKIELAHunter  Professor  of  Mechanical  DesignWashington  University  in  St.  Louis

Syllabus  +  Calendar

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Updated 1/6/2004

MEMS 5104: The CAE-Driven Mechanical Design Process

Lectures M. Jakiela (coord.) 935-4966 mjj@wustl.edu Office hours: T, Th 4-530 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, multi-disciplinary 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 Wednesdays 8/28 Intro and logistics Student version AltairUniversity account 1: Inspire Introduction 2: Inspire Interface

8/30 Install Hyperworks and Inspire

9/4 LABOR DAY – NO Class

9/6 Geometry – Create 3: Geometry – Create & Simplify 3: Exercise: Create Geometry Skill Demo (“SD”) 1: Inspire Interface

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 2017.” 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.

Product  of  Skill  Demo

Product  of  Skill  Demo

Product  of  Skill  Demo

(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 2017.” 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.

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, 5th 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.

Small  Project  1  -­‐ Motivation

Small  Project  1  – Student  Results

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 Inspire1. Choose a different structural part and determine its loading, boundary conditions, and appropriate casting technique. Some ideas2 are:

1. Water well pump handle http://www.handpumps.com/ 2. Foot powered tire/sports-ball air pump lever

http://www.argos.co.uk/product/1479331 3. Vise-grip handle

https://www.toolstation.com/shop/Hand+Tools/d10/Pliers/sd60/Irwin+Vise+Grip+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.

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.

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

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.

Figure'1:'Existing'design'with'applied'loads'and'boundary'condition'

Table 1: Material data

Material Name

Young’s Modulus

(MPa) Poisson’s

Ratio Density (t/mm3)

Yield Strength (MPa)

Part Mass (kgs)

Aluminum (A380) 71000 0.33 2.76E-9 159

0.364 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).

Small  Project  2  – Student  Results

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 project-level problem of your own choosing. Please choose one of the following 5 topic areas1. 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 modules2.

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. 2Recall this is how the skill demos were devised.

Large  Project  – Student  Results

“V  2”  Changes  and  Revisions

• “Pick  up  the  pace”• Increase  coach/student  ratio• Compare  several  tools

• Outputs• Interfaces