MEC2181 Mechanical Simulation - Introduction to Simulations.pdf

SIT Internal 1 MEC2181 Mechanical Simulation 4 or 5 September 2024 Introduction to simulations Introduction to ANSYS workbench Thermal analysis By: Elisa Ang...

SIT Internal 1 MEC2181 Mechanical Simulation 4 or 5 September 2024 Introduction to simulations Introduction to ANSYS workbench Thermal analysis By: Elisa Ang Email: [email protected]  SIT Internal Hello! About me  Name: Elisa Ang  Education: BEng (Hons) Aerospace Engineering at NTU, Singapore MSc Computer Engineering at Uni-FAU, Germany Topics for today MSc Applied Mathematics at TU Delft, The Netherlands PhD at NTU, Singapore (Simulations)  Jobs: Joined SIT as a faculty member on 2nd Jan 2020 Researcher at TU Delft from Aug 2015 to Dec 2015 Senior Engineer (Air Systems) at DSTA Singapore from Jul 2010 to July 2013  Email: [email protected]  telegram @elisaaym. 2  SIT Internal Your other instructors Dr Lim Yau Shiang Prof Victor Wang (CFD) Dr Peter Beshay Dr Zhang Lanyue Dr Naseeb Siddiqui 3  SIT Internal Module learning outcomes Describe the process of discretization to form numerical solutions Formulate a numerical model representing real-world applications in ANSYS Validate the numerical model using physical measurements or with analytical solutions 4  SIT Internal Week Date Location Tutorial/workshop Topic 1 Module plan 4 Sept 2024 (T1) NP-SR3C,NP-SR3D 3 hrs tutorial Introduction to simulations 5 Sept 2024 (T2) Introduction to ANSYS workbench 6 Sept 2024 (T1, NP-SR3C,NP-SR3D 2 hrs workshop/project Brainstorming on project / Self practice followed by T2) activities (total 4 hrs) 2 11 Sept 2024 (T1) NP-SR3C,NP-SR3D 3 hrs tutorial Mesh dependence study 12 Sept 2024 (T2) Transient thermal analysis Introduction to processing tools in Ansys thermal analysis 13 Sept 2024 (T1, NP-SR3C,NP-SR3D 2 hrs workshop/project Brainstorming on project / Self practice followed by T2) activities (total 4 hrs) 3 18 Sept 2024 (T1) NP-SR3C,NP-SR3D 3 hrs tutorial CFD workshop part 1 (external flow) 19 Sept 2024 (T2) 20 Sept 2024 (T1, NP-SR3C,NP-SR3D 2 hrs workshop/project Brainstorming on project / Self practice followed by T2) activities (total 4 hours) 4 25 Sept 2024 (T1) NP-SR3C,NP-SR3D 3 hrs tutorial CFD workshop part 2 (transient internal flow) 26 Sept 2024 (T2) 5 02 Oct 2024 (T1) NP-SR3C,NP-SR3D 3 hrs tutorial Quiz 03 Oct 2024 (T2) 8 25 Oct 2024 (T1, NP-SR3C,NP-SR3D 2 hrs workshop/project Self practice/ work on project followed by T2) activities (total 4 hrs) 9 1 Nov 2024 (T1, NP-SR3C,NP-SR3D 2 hrs workshop/project Self practice/ work on project followed by T2) activities (total 4 hrs) 10 7 Nov 2024 NP-SR6C,NP-SR6D,NP-SR6E Catered for 5 hours. 30 mins Project presentation for each group. Split into 3 5 parallel tracks  SIT Internal Assessment Pre-module assignment (10%) – submission by 6th September 2024 Individual quiz on Week 5 (25%)  MCQ  Face to face proctored examination  45 mins, 30 questions Group report on Week 6 (30%)  Report on ideation of project topic  Proposed methodology on how the simulation/experiment is going to be designed Final project presentation on Week 10 (35%)  15 minutes presentation  15 minutes Q&A  Peer reviewed 6  SIT Internal Pillars of science and engineering Typical development pathway in science and engineering  We postulate theories on how things work and why  Then we design experiment to validate the findings Adapted from Tobias Weinzierl (2022). The Pillars of Science. Adapted from Tobias Weinzierl (2022). The Pillars of Science. Aristotle: 𝑚𝑚1 > 𝑚𝑚2 → 𝑇𝑇 𝑚𝑚1 < 𝑇𝑇(𝑚𝑚2 ) Galileo Galilei: 𝑚𝑚1 > 𝑚𝑚2 → 𝑇𝑇 𝑚𝑚1 = 𝑇𝑇(𝑚𝑚2 ) 7  SIT Internal Pillars of science and engineering However, theory and experiments can be limiting.  Some experiments are economically infeasible – designing of aircraft wings Some experiments are ethically inappropriate. – Novel ways of radiation treatment/design of a new construction like bridge Some experiments are ecologically dubious. – Design novel nuclear reactors Some experiments are by construction impossible. – Big bang Some equations are so complex that we cannot solve them (analytically). – we will see some of them later With advance in computing, a third support pillar has emerged - simulations Adapted from Tobias Weinzierl (2022). The Pillars of Science. 8  SIT Internal What are computer simulations Computations, using computers, that calculates how a system behaves over time given certain rules and behaviours, in a way that is unattainable for any group of humans https://www.scienc edirect.com/scienc e/article/pii/S0009 250915000779 Field based or particle based http://www.hanleyin novations.com/cartgr id.html 9  SIT Internal Building Blocks of computer simulations 10  SIT Internal e.g. particle based simulations 1. Underlying governing and interactions law 𝐹𝐹 = 𝑚𝑚𝑚𝑚  Imagine we are in a ball universe.  In this universe, when two balls are too close 1N 1N together, they experience opposing force of 1N 2. Initial and boundary conditions 3. Discretization methods 𝑑𝑑𝑑𝑑 𝑣𝑣𝑓𝑓 −𝑣𝑣𝑖𝑖  𝑎𝑎 = = 𝑑𝑑𝑑𝑑 ∆𝑡𝑡 1kg 1kg 1kg 𝑑𝑑𝑑𝑑 𝑑𝑑𝑓𝑓 −𝑑𝑑𝑖𝑖  𝑣𝑣 = = 𝑑𝑑𝑑𝑑 ∆𝑡𝑡 Ball 1 Ball 2 Ball 3 All balls at rest initially (𝑣𝑣𝑖𝑖 = 0 𝑚𝑚/𝑠𝑠) 11  SIT Internal What will happen to the 3 balls after 1s? 1kg 1kg 1kg Ball 1 Ball 2 Ball 3 All balls at rest initially (𝑣𝑣𝑖𝑖 = 0 𝑚𝑚/𝑠𝑠) 1kg 1N Lets consider Ball 1. According to the laws of the ball universe Ball 1 F=1N 𝐹𝐹 Newton’s second law – find acceleration 𝑎𝑎 = = 1𝑚𝑚/𝑠𝑠 2 𝑚𝑚 Integrator – find final velocity 𝑣𝑣𝑓𝑓 = 𝑣𝑣𝑖𝑖 + a∆t = 1 𝑚𝑚/𝑠𝑠 Assuming ∆t=1s – find final position 𝑑𝑑𝑓𝑓 = 𝑑𝑑𝑖𝑖 +𝑣𝑣𝑓𝑓 t = 1 𝑚𝑚 12  SIT Internal What will happen to the 3 balls after 1s? Time = 0s 1kg 1kg 1kg Ball 1 Ball 2 Ball 3 Time = 1s 1kg Ball 1 13  SIT Internal Activity 2: What-3 will-2happen -1 0 to the 1 ball 2 2 3 and ball 3 after 1s? Ball 1 Ball 2 Ball 3 Time = 0s 1kg 1kg 1kg 1kg Step1: Draw the free body 1kg Step1: Draw the free body diagram. What force is Ball 2 diagram. What force is Ball 3 experiencing? experiencing? Ball 2 Step2: Newton’s second law – find Ball 3 Step2: Newton’s second law – find acceleration acceleration Step 3: Integrator – find final Step 3: Integrator – find final velocity velocity Step4: Integrator - find final Step4: Integrator - find final position position Final position of Ball 2 is ? Blank 1 Final position of Ball 3 is ? Blank 2 14  SIT Internal Activity 2: What will happen to the ball 2 and ball 3 after 1s? Ball 1 Ball 2 Ball 3 Time = 0s 1kg 1kg 1kg Time = 1s 1kg 1kg 1kg Ball 1 Ball 2 Ball 3 15  SIT Internal Many balls in Ball universe that has gravity A more complicated system, but based on the same laws 16  SIT Internal Why is it growing increasingly important? 17  SIT Internal Growing importance Growing complicity of problems & increase in computing power  The problem we had to deal with in the past is maybe smaller scale, simpler problems  Right now, most of the problems we need to solve are of larger scale, with more interactions  For some problems, computational methods seems to be the only systematic means of making progress 18  SIT Internal Different scales and applications 19 Scales of equation-based simulations And someSIT Internal applications Vlachos, D. G. (2012), Multiscale modeling for emergent behavior, complexity, and combinatorial explosion. AIChE J., 58: 1314-1325. doi:10.1002/aic.13803 20  SIT Internal Atomic/molecular level https://greenliving.lovetoknow.com/en vironmental-issues/how-desalination- plants-work. 21  SIT Internal Application 2: Traffic simulation Traffic simulations method span across various scale  Microscopic level  Every vehicle is considered an individual, so every vehicle has its own governing equation. Much like in molecular dynamics  Each vehicle has their own speed, acceleration, individual driver-vehicle interaction  VISSIM, CORSIM, AIMSUN, PARAMICS 22 Microscopic level – example PARAMICS  SIT Internal Application 2: Traffic simulation Traffic simulations method span across various scale  Macroscopic level – continuum approach  Similar to field-based simulations. There is a system of overarching governing equations with variables such as density (𝜌𝜌) and flow rate of traffic stream (𝑞𝑞) Macroscopic level, e.g. AIMSUN  Solve the system wrt time and space  Modelled after fluid flow theory 23  SIT Internal Application 3: Train flow simulation Based on physics (satisfy the navier stokes and general heat conduction equation) And the boundary/initial conditions For e.g. aircon temperature, flow rate, ambient and outdoor temperatures predict the temperature distribution within the train 24  SIT Internal Focus for this module 25  SIT Internal Macroscopic simulations In this course, we will mainly be using ANSYS workbench to design simulations – looking at continuum level simulations  Some other alternatives Solidworks OpenFOAM Comsol Abaqus SimScale 26  SIT Internal Types of analysis depends on governing equations Static or transient thermal analysis: General heat Week 1 and 2 conduction equation Computational Fluid Dynamics analysis: Navier Week 3 and 4 Stokes equations 27  SIT Internal Introduction to numerical methods Using heat conduction analysis as an example 28  SIT Internal Content Go through the Pre-Lab exercise on Introduction to Numerical Method  Using ANSYS to solve for the same problem 100 ℃ 225 ℃ 50 ℃ 0℃ 29  SIT Internal Pre-lab exercise *ingredient 2: boundary conditions. Note: for steady state simulations, no need for General heat conduction equation initial conditions without heat generation No internal heat 𝑑𝑑𝑑𝑑 𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕 𝜕𝜕𝜕𝜕 generation 𝜌𝜌𝑐𝑐𝑝𝑝 = 𝑘𝑘 + 𝑘𝑘 + 𝑘𝑘 + 𝜔𝜔̇ 𝑑𝑑𝑑𝑑 𝜕𝜕𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕𝜕𝜕 𝜕𝜕𝜕𝜕 Further assume  Steady  2D  k is constant 𝜕𝜕 2 𝑇𝑇 𝜕𝜕 2 𝑇𝑇 *ingredient 1 + =0 𝜕𝜕𝑥𝑥 2 𝜕𝜕𝑦𝑦 2 – governing law 30  SIT Internal Pre-lab exercise Every numerical method starts with discretization  Let’s discretize the domain: 100 ℃ *ingredient 3: discretization 𝑇𝑇1 = 𝑇𝑇2 = 225 ℃ 50 ℃ 𝑇𝑇3 = 𝑇𝑇4 = 0℃ 31  SIT Internal Pre-lab exercise Every numerical method starts with discretization  Now lets discretize the governing equation 𝜕𝜕 2 𝑇𝑇 𝜕𝜕 2 𝑇𝑇 + =0 𝜕𝜕𝑥𝑥 2 𝜕𝜕𝑦𝑦 2 𝜕𝜕2 𝑇𝑇 𝑇𝑇(𝑥𝑥+∆𝑥𝑥,𝑦𝑦)−2𝑇𝑇(𝑥𝑥,𝑦𝑦)+𝑇𝑇(𝑥𝑥−∆𝑥𝑥,𝑦𝑦) 𝜕𝜕 2 𝑇𝑇 𝑇𝑇(𝑥𝑥, 𝑦𝑦 + ∆𝑦𝑦) − 2𝑇𝑇(𝑥𝑥, 𝑦𝑦) + 𝑇𝑇(𝑥𝑥, 𝑦𝑦 − ∆𝑦𝑦) ≈ ≈ 𝜕𝜕𝑥𝑥 2 ∆𝑥𝑥 2 𝜕𝜕𝑦𝑦 2 ∆𝑦𝑦 2 4𝑇𝑇(𝑥𝑥, 𝑦𝑦) = 𝑇𝑇(𝑥𝑥 + ∆𝑥𝑥, 𝑦𝑦) + 𝑇𝑇(𝑥𝑥 − ∆𝑥𝑥, 𝑦𝑦) + 𝑇𝑇(𝑥𝑥, 𝑦𝑦 + ∆𝑦𝑦) + 𝑇𝑇(𝑥𝑥, 𝑦𝑦 − ∆𝑦𝑦) 32  SIT Internal Pre-lab exercise 4𝑇𝑇(𝑥𝑥, 𝑦𝑦) = 𝑇𝑇(𝑥𝑥 + ∆𝑥𝑥, 𝑦𝑦) + 𝑇𝑇(𝑥𝑥 − ∆𝑥𝑥, 𝑦𝑦) + 𝑇𝑇(𝑥𝑥, 𝑦𝑦 + ∆𝑦𝑦) + 𝑇𝑇(𝑥𝑥, 𝑦𝑦 − ∆𝑦𝑦) Consider 𝑇𝑇1 4𝑇𝑇1 = 𝑇𝑇2 + 225℃ + 𝑇𝑇3 + 100℃ Task 1.1: Find similar equations for 𝑇𝑇2 , 𝑇𝑇3 and 𝑇𝑇4 33  SIT Internal Pre-lab exercise Task 1.1: Solve for 𝑇𝑇1 , 𝑇𝑇2 , 𝑇𝑇3 and 𝑇𝑇4 4 equations, 4 unknowns → solve simultaneously 34  SIT Internal Question What if we need to know the temperature distribution with finer grids 35  SIT Internal A note on FDM, FVM and FEM Finite difference (FD) vs finite volume (FV) vs finite element (FEM)  FD – continuous function, structured domain, apply differential form of the governing equation (what we have seen so far)  FV – discontinuity can be handled, apply integral form of the governing equation (ANSYS)  FEM – apply weak form of the differential equation, a lot easier to have better accuracy, works for complex domain (ANSYS) 36  SIT Internal Part 1: flat plate We will solve the same problem, but this time using ANSYS First lets start up ANSYS Take note of the green tick! It means the step is completed Please save your workbench as Week1_lab 37  SIT Internal Part 1: 2D plate Step 2: next we specify the engineering data 38  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) 39  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) Select new sketch plane, and select the xy plane 40  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) 1. Select rectangle geometry 2. Create a 10mm by 10mm square 41  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) Select end sketch A surface is generated editing 42  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) Select pull, and click on the surface you just generated Click “space” and type 100mm to make 1 very long 10mm by 10mm rod. Note that this is essentially 2D in the xy plane in terms of heat transfer 43  SIT Internal Part 1: 2D plate Step 3: Create geometry  Right click on geometry, select “new SpaceClaim Geometry” (Note you can also use solidworks and import the geometry into SpaceClaim if you wish) 2. Just click close. U do not have to explicitly save the geometry file, as this is also saved in your 3. The space claim file workbench files. you just created can 1. Click select and However, if you wish, be found in the notice that a solid is u can explicitly save Week1_lab_files generated now it. folder, under dpo- >SYS->DM 44  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Double click on model to open up ANSYS mechanical 2. Click on Geometry, then SYS\Solid 1. Project tree is a good reference for the steps required in the analysis. Again green tick implies minimum information required for analysis is there. 2. Here under Material Assignment, you can choose the material of your solid. (Materials in your engineering data library are shown here). For now, we 45 keep as structural steel  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Generate mesh 2. Then click sizing 3. Ensure that body selection is enabled 1. Next click on mesh in the project tree 46  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve 4. Then click on  Generate mesh generate mesh 1. Click the body 2. Click on geometry, and then apply 3. Next click on element size and enter 0.001 (1mm element size) 47  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Generate mesh 1. Click on mesh on the project tree again to see the generated mesh 48  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Input boundary conditions – in our simple example, all BCs are constant temp 1. Right click on “steady state thermal) -> insert -> temperature 49  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Input boundary conditions – in our simple example, all BCs are constant temp 1. Ensure that face selection is enabled 2. Click on the left face, click geometry and click apply 3. Click Magnitude, Set the temperature as 225 ℃ and click apply 50  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Repeat for the other 3 sides 51  SIT Internal Part 1: 2D plate Step 4-6: Define model, setup and solve  Now we solve! Before that, lets set up the temperature contour results 2. Then click solve 1. Right click on Solution -> Insert -> Thermal -> Temperature 52  SIT Internal Part 1: 2D plate Step 7: post-processing (to change to front view, go to Display, 1. Click on Display -> Views -> Front view 53  SIT Internal Some extra practise How does this compare with your calculated results?  Which do u think is more accurate? Prelab, or what we have just done? Can u change the material of the system? Can u change the boundary conditions to make one side insulated? Can u include internal heat generation for the plate? 54  SIT Internal Lab tour on friday Pls be in long pants/covered shoes. 55