You’re the CEO of a product development organization. Your engineering team has designed what you expect to be a great product. So it’s off to mass production, right?
Not so fast. Before that, you have to define how you’re going to manufacture it. Before that, you want assurance that the product will work. It shouldn’t break too easily or be overbuilt and last forever (planned obsolescence). You will build a prototype and test it, but that’s expensive too. How can you validate and verify your product quickly at low lost? Simulation analysis is the answer.
In CAD, simulation analysis is the process of developing a mathematical representation of an actual or proposed product in a computer model .
Engineers often simulate thermal, modal, and structural properties of models.
Prototyping versus Simulation
Admiral Hyman Rickover, father of the US nuclear navy, was famous for advocating duplicating, not simulating. When you have the time, resources, and finances, it is always preferable to build full-scale prototypes and test them under actual operating conditions. But if you’re trying to get to market fast --faster than your competitors--and at low cost, this isn’t always feasible or advised; moreover, it can be dangerous. Having humans operate prototype hardware without simulation analysis to verify and validate safety puts them in harm’s way .
Admiral Rickover father of modern Navy and presumably well-funded advocate of physical prototyping. [By Unknown - U.S. Naval Historical Center official site, Public Domain]
To make product development faster, less expensive, and safer, scientists and engineers began harnessing the power of computers to simulate and analyze complex engineering problems, beginning as early as the 1940s. This marked the beginning of the modern era of simulation analysis.
Predicting Real-World Results with Simulation in CAD
With simulation in CAD, potential real-world conditions and environments are applied to a model to reproduce what its real-world analog would experience. This produces numerical results for how we describe the reactions and end states of the product, often depicted in visual forms and animations.
Simulation analysis intends to verify that the product meets its requirements for operation. It can further provide insight into necessary changes and validate that the correct real-world tests are conducted. You can eliminate tests when you have high factors of safety, conduct the tests for the requirements in which your margins are borderlines – and redesign for the conditions that you fail.
Simulation analysis for engineering product development can take many different forms, including but not limited to:
- Finite Element Analysis (FEA).
- Computation Fluid Dynamics (CFD).
- Rigid Body Kinematics and Dynamics.
Within the field of FEA, many different types of analyses can be performed, such as static, dynamic, modal, steady-state thermal, transient thermal, and fatigue.
Simulation Analysis in Design
Engineers learn how to derive and calculate closed form solutions for situations such as:
- Deflection and stresses of a cantilevered beam under uniform load.
- Equilibrium temperature of a block subject to known heat loads.
- Cycles to failure by crack propagation.
However, closed-form solutions don’t exist for complex products consisting of multiple components, with irregular shapes, and a combination of materials like those seen in industries like aerospace and defense, consumer electronics, medical devices, and automotive.
Therefore, simulation analysis takes a “divide and conquer” approach to evaluating problems for which no closed form solution exists. FEA breaks up a model into numerous small elements, like tetrahedra (pyramids), wedges, and bricks, for which closed-form solutions are available. These elements are composed into a “stiffness matrix.” When constraints are applied to the model, the stiffness matrix reduces down to a solvable number of equations.
For given forces applied to a model, we can calculate the displacements, from which we can calculate strains (change in length compared to initial length), and then the stresses. This information tells us whether the object can withstand its operating conditions, or if it will permanently deform or break.
In addition to the product’s geometry, “divide and conquer” can also be applied to other aspects of the analysis, like loads and time. For example, when simulating contact and impact, the load can be applied in increments, since the stresses increase non-linearly as the contact area increases. Thermal, fluid dynamics, and mechanism analyses break up the time domain into small increments to compute incremental changes.
Often the final numerical result of simulation analysis is the calculation of the factor of safety and margin of safety. The two are mathematically related and provide a bottom line answer regarding whether the product can withstand the loads of its operating environment.
If our product meets its margins of safety, we can use the results to enter redesign cycles to optimize the product. In this way, simulation analysis can help make the product lighter, more aesthetically pleasing, and more easily manufactured.
Simulation Analysis and Testing
Simulation analysis should always be followed up with real-world tests. As Admiral Rickover knew, simulation analysis is not a substitute for testing, but validates that we are performing the correct tests (the ones at or below the borderline). The combination of simulation analysis and testing forms the verification process that ensures our product meets requirements and intent.
Simulation analysis is critical to the product development process, using computer power to help us define the best product for our needs, as quickly, affordably, and safely as possible.
