As a PhD student at the University of Michigan, Joseph Rakow’s research carried him from advanced composites laboratories into failure analysis. Rakow has expertise in structural and mechanical engineering with emphasis on composites. As a failure analysis associate, companies call on him to figure out the how and why of a composite failure in their product.

Joseph F. Rakow, managing engineer at Exponent Failure Analysis Associates, discusses his experience with composite flaws.

Joseph F. Rakow, managing engineer at Exponent Failure Analysis Associates, discusses his experience with composite flaws.

As a failure analyst, what industries do you cover?

Because I’m in a consulting role, I’m involved with people from various industries. I mostly investigate composite failures in airplane accidents, broken pipelines, fire-damaged wind turbines and injuries involving sporting equipment. It’s my job to look at what happens when things break, what causes it to break or led to its failure.

What’s the biggest accident analysis you’ve conducted?

The biggest issue I’ve seen was in RV manufacturing. The company made sidewalls for the inside of the RV from glass-reinforced polymers. For a long time, they were buying face sheet material from a composite manufacturer. They would take a sheet and make a wall. Everything was going fine until at one point they were getting significant wrinkling, which obviously made customers upset. We did an investigation and uncovered that the supplier of the outside face sheet had recently changed its emissions handling processes to comply with EPA regulations. Part of the change was a switch in the manufacturing and curing parameters, so the parts weren’t achieving full cure and therefore they were shipping them undercured to the RV manufacturer. The parts weren’t completely cured until after the RV was made. During this time, the styrene off gas was eating away at the styrofoam core, making it wrinkly. A bunch of customer complaints led to refund requests and lawsuits. In the end, the RV manufacturer went out of business and the composite wall supplier spent more money than they needed to in order to fix the problem.

What common mistakes do composites manufacturers make?

There are common things like voids, air bubbles, under-curing of a material and not using appropriate materials, or if the part is laminated, layers are missing. The majority of the time we find companies have processes and quality controls set up to make sure it produces quality products, but bad products do slip through. Sometimes a quality control system wasn’t robust enough or something changed within the product, which can happen without them knowing. For example, a supplier changes an ingredient without warning the manufacturer.