LO1 Explore the capabilities and limitations of computer-based models in meeting design fundamentals and their use in solving problems in engineering.

Technical Education Centre Open Learning – BTEC Level 5

UNIT E5004

Computational Modelling in Virtual Engineering

Section 1 out of 2

Computer modelling and FEA

Introduction

The work of an engineer increasingly involves the use of powerful software modelling tools (virtual modelling). These tools allow us to predict potential manufacturing difficulties, suggest how a product or component is likely to behave in service, and undertake rapid and low cost design iteration and optimisation, to reduce costs, pre-empt failure and enhance performance.

On successful completion of this unit students will be able to consider how to perform computational fluid dynamics (CFD) simulations, develop finite element product and system models, explain the identification of faults in the application of simulation techniques and discuss the modelling method and data accuracy.

The Learning Outcomes covered in this unit are:

LO1 Explore the capabilities and limitations of computer-based models in meeting design fundamentals and their use in solving problems in engineering.

LO2 Develop finite element model(s) in order to find and solve potential structural or performance issues.

1.1 Capabilities and limitations of computer-based models

At this stage in your studies, and from your own experience possibly in your employment, you shall have encountered some 2D and 3D design packages and have had the chance to become familiar with their operations and their uses.

CAD refers to computer-aided design, which is a creative design process that is done using a computer system. Its software, the CAD design program, is widely used by professionals in the design field that requires much precise technical drawings. However, it is not like other drawing programs where you can simply open and begin drawing. It requires a combination of tools and mathematical equations to get started, and in order to get the design precise. As it is not easy to master the program, people are trained to become professionals in order to use the program.

Some Advantages of CAD:

1. Saves time: When you are using the computer-aided design software, it will save your time and you can make better and more efficient designs in shorter time duration.

2. Easy to edit: When you are making designs, you may find the need to make alterations. When you are using computer-aided design software, it will be much easier to make any changes because you can fix the errors and modify the drawings easily.

3. Decrease in error percentage: As the CAD software makes use of some of the best tools, the percentage of error that occurred because of manual designing is significantly reduced.

4. Decrease design effort: When it comes to the amount of effort that was needed for the sake of designing the different models, it has been reduced significantly because the software automates most of the task.

5. Code re-use: As the entire task is carried out with the help of computer tools, it removes the problem of duplication of labor, you can copy the different parts of code and design which can then be reused multiple times over and over again.

6. Easy to share: The CAD tools make it easier to save the files and store it in a way that you can use it time and again and send it without any unwanted hassles too.

7. Improved accuracy: There is absolutely no doubt about the fact that the kind of accuracy that CAD software will offer can never be achieved by opting for manual drawings. You have tools to measure the precision, skill and accuracy level of the designs.

8. Can you think of some others here of your own?

Some Disadvantages of CAD:

1. Work can be lost because of the sudden breakdown of computer systems

2. Work is prone to viruses

3. Work could be easily “hacked”

4. Time taking process to know how to operate or run the software

5. High production or purchasing cost for new systems

6. Time and cost of training the staff which will work on it

7. Need of regular updating of software or operating systems

8. Needs less employment because of CAD/CAM systems

9. Can you think of some others here?

As a result of other areas of technology, we can expect that CAD will continue to develop in the future, opening up new and innovative methods of design and engineering for a number of different industries. This will aid in making users experiences of CAD equipment more intuitive and simple than they ever thought possible.

Computer modelling and simulation

BBC provide the following useful information (below) which summarises the basics on computer based modelling and simulation and is relevant to this unit.

In computing, modelling is used to look at large amounts of data to help with scientific or engineering projects. Simulations are used to graphically represent how things might look and feel.

A computer model is a representation of a real-life system or situation, such as the workings of a nuclear reactor or the evacuation of a football stadium.

A collection of rules is created to study what would happen in real-life situations. Changes are made to see how they affect the outcome. For example, before a new football stadium is built, a computer model could be used to see if there are enough fire exits and if they’re in the safest places.

Simple models can be built in a spreadsheet. A spreadsheet model could be used to plan a school prom. To make sure it came in on budget the spending on food, drinks, entertainment, and the price of tickets could be varied.

It could also be used to see how much money would be made from ticket sales.

These are called `what if…` questions, for example:

• What if only 20 people attend?

• What if costs go up by 10 per cent?

More complicated models can be built to replicate real-world phenomena such as water, fire and weather. Watch the clip below to see how computers can be used to model special effects in films.

Computer models - Modelling and simulation - BBC

Simulations

Simulations are a type of computer model. A simulation imitates a particular environment. It can be used for research or training.

Pilots are initially trained using a flight simulator. The simulator consists of a cockpit that is identical to the cockpit in a real plane. The windows are replaced with computer screens that show a simulation of the outside world. The screens, cockpit displays and controls are linked to a powerful computer that responds to the pilot.

The simulation reacts based on predetermined rules linked to how the pilot behaves.

Advantages of a flight simulator

The pilot can learn the basics without any risk of damaging the plane or injuring passengers and crew.

It is cheaper than buying and maintaining a real plane for training purposes.

No fuel or crew is required.

The pilot can practise flying in dangerous weather conditions, eg heavy wind and rain.

The pilot can practise what to do in emergencies, eg engine failure.

Other uses of simulation

Nuclear power stations use simulation to improve output by looking at temperature, pressure and gas flow in the plant.

Scientific experiments, eg plant growth, can be simulated in varying conditions.

Studying the effect of the sea on the coastline in order to position defences to protect against erosion and flooding.

Investigating the need for new roads or traffic lights by simulating traffic flow.

The aerodynamics of cars can be investigated by simulating air flow over different body shapes.

Advantages and disadvantages of modelling and simulation

A model or simulation is only as good as the rules used to create it. It is very difficult to create an entirely realistic model or simulation because the rules are based on research and past events.

The main disadvantage of simulations is that they aren’t the real thing. People may react differently when faced with situations in the real world. For example, they are more likely to panic if there is real danger.

With the increase of virtual worlds, people are becoming more familiar with simulation. This familiarisation increases real-world reactions in virtual environments.

Advantages of modelling and simulation

Can be safer and cheaper than the real world.

Able to test a product or system works before building it. Can use it to find unexpected problems.

Able to explore ‘what if…’ questions.

Can speed things up or slow them down to see changes over long or short periods of time.

Disadvantages of modelling and simulation

Mistakes may be made in the programming or rules of the simulation or model. The cost of a simulation model can be high.

The cost of running several different simulations may be high. Time may be needed to make sense of the results.

People’s reactions to the model or simulation might not be realistic or reliable.

Computer games or video games are based on ‘what if…’ questions. They are becoming increasingly sophisticated and allow for more complex real-life simulations. There is software available that allows anyone to create their own computer game or virtual world.

Recent NEWS

We are now all too familiar with this type of computer based modelling hitting our News screens Daily News Story 5-24-2020 - YouTube

Here is an interesting clips on another industrial use of simulation software:

Simpleware Ltd.

1.2 FEA (Finite Element Analysis)

Finite element analysis (FEA) is used in order for engineers to predict the behaviour of systems and parts, typically in the areas of heat transfer, electromagnetic potential, fluid flow and structural analysis amongst others. These systems can be static or dynamic and one, two or three dimensional. To predict the behaviour of a system, FEA looks at it in terms of a number of algebraic equations rather than the system as a whole. The problem is divided into a large number of much simpler parts, known as ‘finite elements’ and brought together at the end of the process to give an overall answer. 

FEA of: Aircraft engine                              Automotive engine

Note: In the FEA images high Compressive strains are noted by blue colours, high tensile strains are noted in red, low strains are noted as light blue/green/yellow.

The FEA software component of SimScale enables you to virtually test and predict the behavior of structures and hence solve complex structural engineering problems subjected to static and dynamic loading conditions.

The FEA simulation platform uses scalable numerical methods that can calculate mathematical expressions that would otherwise be very challenging due to complex loading, geometries, or material properties.

Watch this simulation here: https://youtu.be/UlrnGyrzRmo

With regards to structural analysis, FEA is used very frequently in functions such as calculating the failure point of parts and structures when put under load. In order to make a simulation of a structure, a ‘mesh’ is created which consists of a huge number of small elements, which when added together make up the structure overall.

These individual elements produce known values at each corner and these points are called nodal points or nodes. When each individual element and node has been worked out, the mesh can be converged, and an overall result obtained. If a more precise overall result is required then the mesh can be refined, which is essentially reducing the size of each individual element to reduce errors in calculations.

The mathematical form of FEA is a complex and time-consuming process, therefore computer-based models are used to predict this behaviour, the visualisation of the end product is also very effective at quickly communicating issues in design to the designer(s).

As with any prediction, the results cannot be guaranteed to be exactly 100% accurate. It is therefore prudent to check the results of the simulation against historically similar systems; experienced engineers usually have an idea of the expected results and can therefore identify erroneous simulation results. Simple hand calculations can also be carried out to confirm simulated results on more simple systems such as single beam deflection. The same simulation can also be carried out by another engineer and/or using different software to confirm the simulation results are accurate.

Simscale

Simscale is a very useful software that we will become familiar with in order to be able to satisfy the requirements of our assessments for this unit. Create your own free account for use here.

Watch this video here on getting started with Simscale Getting Started with SimScale | Webinar - YouTube

Although the learning materials for this section are not lengthy there is a requirement that you are familiar with the basics of FEA software and therefore we require you to download and create a free SimScale account for yourself so that you can then take advantage of the animation simulations for FEA.

You will need to familiar with this software somewhat for your assessments. See below: 

1. Simulation Software | Engineering in the Cloud | SimScale – Use this link to create a free account.
2. FEA For Beginners – Finite Element Analysis | SimScale – View this page and click on the car suspension project to open this on your computer (shown below) 
3. Follow this short instructional video that we have produced to teach you how to develop this basic FEA model for the car suspension. View our animated simulation showing the FEA for the product (hopefully you can follow this easily) – https://youtu.be/vRXh5EyYDHs
4. Now try this same modelling yourself to practise for your assessment as you will be doing something very similar.
5. Now try the wing simulation here and see if you can animate using the same method through the link below and try out some of the other simulations available on the SimScale website (all free of charge!).

FEA of aircraft_wing_homework | SimScale

You can clearly see the red areas shown on the wing indicating areas of maximum stress for this structure. These are obviously the areas that pose greatest risk and could be examined and possibly redesigned if necessary to try to reduce the likelihood of component failure.

Visit the SimScale FEA page here FEA Software | Finite Element Analysis in the Cloud | SimScale which is a great resource.

Case Studies:

View the Case Studies and here is one that we recommend that you take some time to read (interesting) and note that this uses CFD (Computational Fluid Dynamics) and not FEA which we will be looking at in Section 3 for this unit.

Germain Racing Tests NASCAR Race Car Design with CFD | SimScale