Computer simulation allows replacing a real design, technological or physical process by a virtual one. When is it necessary? Almost always when we develop something new.

Stages of preparation and computational analysis

An engineer develops a new technological process or a designer designs a new part, for example, a motor hood. How to check what will happen to this hood, for example, on impact with another car or an obstacle. Earlier it was manufactured, then installed on a real car and after that it was required to run this car into another one or a wall. All of that resulted in high financial costs. And imagine that you need to work at, let's say, 100 design options of the hood. How much money will you have to invest in it? A vast amount of money! What should we do? The answer is to use computer simulation and transfer the entire process to a computer. I mean to perform these 100 collisions or crash tests using a virtual car but not a real one.

 What is required for that? You need computer simulation software, a computer or a highly-performance cluster and a person who can do it. So, all those people who were involved in the manufacturing of a hood prototype are replaced by 1-2 persons - a designer and a computing engineer.

What does computer simulation allow do to? Almost anything. It allows developing a new technological process, creating a new safe car, designing and testing aerodynamic characteristics of a new aircraft and a lot more.

Let's have a look at the stages of development of a new bending tool for aircraft parts manufacturing in the LS-DYNA program. All these stages are applicable to any other area, whether it is a car crash test or calculation of a simple design.

 

Fig. 1. Stages of preparation and computational analysis in the development of a new bending tool for aircraft parts manufacturing

First, in accordance with the detail drawing, an engineer develops a technological scheme - it is a sequence of operations, for example, in a die or bending rollers. After that he/she develops a tool in 2D or 3D views. Then a computing engineer applies a mesh, i.e. creates a finite element model. After that loads are applied and all necessary parameters are entered to perform simulation. Then calculation is carried out. Such a model can be created in different programs - preprocessors Ansys, ls-prepost, femap, etc. - and calculation can be carried out in other programs, for example, Ls-dyna, ansys, abaqus, etc. When calculation is completed, a calculation analysis or the so-called post-processor analysis is performed. The advantage of computer simulation is that the program uses a virtual model to show how it would actually be, i.e. all defects and distortions that would be obtained in reality will be shown by this computer model. And also all the parameters required for the calculation analysis, for example, acceleration by separate units of the car during a crash test. By comparing these accelerations with the permissible values ​​or in case of a defect in the technological scheme, engineers make a decision to introduce certain corrections to the available technological schemes, modes, or designs. The design engineer and the computing engineer introduce changes and all stages of calculation are carried out again. The number of such calculations is indefinite, and as a result, the process or design that complies with the preset parameters without defects or with the required safety parameters is obtained. After that you can safely put the developed process or design into production.

Examples of simulation of highly nonlinear processes are car crash tests, processes of shaping, machining and other processes.

Simulation of a car crash test

Simulation of a car crash test on a computer in LS-DYNA allows reducing the number of real tests by several times. In addition, virtual mannequins of the driver and a passenger identical with real ones can be placed to a virtual car. During the crash test all deformed elements of the car design, maximum accelerations and mannequin damages are analyzed. In case permissible parameters are exceeded, certain car units are changed so that the mannequins have no damage. All this makes the car more safe and comfortable.

Fig. 2. Simulation of a car crash test

(a calculation sheet from www.ccsa.gmu.edu)

Simulation of metal forming processes

Simulation of forming processes in LS-DYNA allows developing new technological processes for sheet-metal stamping and forging, processes of rollforming and other processes. Simulation allows determining the stress-strain state of the work piece and tool, zones and reasons for defects occurrence, energy and strength parameters. All this is required for the development of progressive and cheap technological processes for parts processing.

Fig. 3. Simulation of rollforming processes

Simulation of machining processes

Simulation of machining processes in LS-DYNA allows studying drilling, milling, grinding and other processes related to cutting. The peculiarity of these processes is processes of material separation and destruction. Available programs for nonlinear analysis allow solving these most complicated problems. Thermal effects and the influence of processing speeds are taken into account besides highly nonlinearity and destruction.

Fig. 4. Simulation of drilling processes

Conclusion

Computer simulation tools, for example using the program LS-DYNA, are widely used in the development of new advanced technological processes and different complex designs. However, you need to understand how these programs work and enter correct parameters to get a solution. A person who will use such computer simulation programs for calculation should have proper education.