Composite-Bodied Electric Car Company Finished
Aptera Motors, a California company that was working on a revolutionary electric car is officially out of business. As reported at The Blaze, some videos recently came out that show employees destroying the composite bodies.
The headline reads:
Employees of Failed Electric Car Manufacturer Caught Destroying Car Frames…With Forklifts
The story describes how the company had hoped to revolutionize transportation with an electric car that was extremely efficient with its’ energy usage. Part of this included the use of lightweight construction materials to decrease the mass of the vehicle while allowing for maximum aerodynamics.
Edmunds did a report on the Aptera that is copyrighted 2009
The videos showing the destruction of the car bodies was posted by Youtube user KarenRei.
The bodies look weak in the video, but I am sure that fully-assembled vehicles were designed to have the doors strengthen the passenger areas for crash protection.
Non-Destructive Testing with Ultrasound
Composite materials can become damaged in many different ways. There can also be flaws in the original manufacturing process. Many times it is necessary to identify any damaged areas within the composites layers that cannot be detected with the eye.
Inspection of composites fiberglass and carbon fiber structures may be required for advanced critical applications of composites materials. Identifying any potential problems with the composites structure is extremely important.
Of course problems can be identified through destructive testing-drilling holes, making cuts, etc. It also may be necessary to do testing in a non-destructive manner, i.e. not cutting into the laminate that is being tested.
One method of accomplishing non-destructive testing of composites laminates is using ultrasound. This Youtube video demonstrates the use of this method.
As you can see, the damage is found in this carbon fiber laminate. This information is a flag that can be used to decide whether to make a repair or replace the structure.
Delamination within the fiberglass or carbon fiber part will result in a much weaker structure than the design intended. Other areas of the composites part will be further strained by weaknesses in other areas and may also fail.
This ultrasonic test can help to identify otherwise invisible problems with either the original manufacturing process or damage during the life cycle of the composite part.
Trimming composite parts
I read an article on waterjet cutting of laminates recently, which demonstrated several advantages of using computer-controlled equipment for trimming and adding features to composites structures. Robotic-guided CNC routers have also been used with much success for large 3D shaped parts with much success. While technology is great, it is expensive. With the rest of composites processing being relatively inexpensive, the trimming operation usually follows suit. Most bimetal saws that cut steel can handle fiberglass, but for large production runs where they will wear down, diamond coated tools offer longer life.
Making a cutting guide for a production composite part is relatively easy. I always called it a “splash”, and it can be done similarly to building a part. Just wax up the gelcoated surface of the finished part, lay down a coat of gelcoat, then build a 3/16 laminate. Then mark out the desired cutout shape and allow for the tool setback for the router collar or saw guide. An aluminum channel edge should be added for wear resistance. Drill bushings can be located on this splash to mark where holesaw work needs to be done as well.
Using a guide collar on a router is essential. I was in a shop where they had a 1/4 inch steel plate guide that was the exact size of the hole, and required running the router bit against it to make the cut. There was TONS of wear on the guide and they were going though router bits like crazy. I set them up with a router collar and compensated for the offset on the jig, and it was a whole new world for the trim operators. The router bits lasted several times longer and the cuts were much faster to make.
Damaging the laminate is one of the dangers when cutting or machining composites. Delamination is the biggest risk, ans is diagnosed by a separation of the layers of fiberglass. The resin bond becomes too weak to hold them together. Delamination can be caused by several other things too, but very often it can happen around machined areas from dull tools or operators that are pushing tools too quickly along a cut.
Sponsor
