Under the Skin: How Digital Prototyping Has Dramatically Improved Engineering
Before digital computing hit the scene, the next step in taking ideas off the drawing board and turning them into reality was building prototypes.
Prototypes can be individual parts or complete cars, and once they are built they can be put to the test to see how well they perform and in some cases tested to destruction if necessary. .
Traditional prototyping was a slow and expensive process because, even with the best engineers, the theory was not always confirmed in practice. The constant back and forth between the drawing board and prototypes was expensive and time consuming.
Computer Aided Design (CAD) and Computer Aided Engineering (CAE) to design and simulate product performance have completely changed things, with the inevitable consequence that cars can now be designed, prototyped and tested in a world virtual before physical prototypes are built. Manufacturers can get closer than ever to the end result before prototypes hit a wind tunnel or a test track.
Porsche’s next-generation Macan is a case in point. The company has created 20 virtual prototypes for different purposes, from aerodynamics to power management and acoustics. Their simultaneous use not only allows engineering teams to identify faults, but also to detect design conflicts between different disciplines when assembling a complete virtual car.
With perhaps a greater emphasis than usual on aerodynamics to minimize drag and maximize the range of the electric sports SUV, aero experts were able to get acquainted with a virtual prototype very early on. They started working on a flow-through model around 2017, and the finishing touches are now being made to details like the cooling ducts. That’s right: virtual prototyping and simulation has now become so precise that it can take into account temperature changes on the performance of components and the car.
A less obvious aspect of the difference between electric vehicles and conventional ICE cars concerns the temperature control and management of the electric transmission – or, in engineering terms, thermodynamics.
An EV cooling system is completely different from that of an ICE car. A fuel tank does not need cooling, but a high voltage drive battery does require careful thermal management. Electric motors and power electronics too; Modern combustion engines operate between 90 and 120 degrees Celsius, while various elements of an electric powertrain operate between 20 and 70 degrees Celsius. Adjusting the aerodynamics to reduce the range can be at odds with using airflow to cool components, causing drag, so the two disciplines go hand in hand.
Before digital prototyping, rapid prototyping of vehicle components was in full swing. CAD driving multi-axis milling machines (machine tools) capable of creating complex shapes from a variety of materials has made it possible to create prototype components without going through full production tooling. It also became possible to make prototype manufacturing tools such as the dies (molds) used to press body panels. They are normally made at enormous cost from high carbon steel, but softer prototype dies can be made quickly from the alloy and, although they are of short duration, allow short series of pressings for evaluation.
So, digital and rapid prototyping not only saved manufacturers money, but also gave us cars with less compromise.