Design/manufacturing flaws: Will the avoidable be avoided in future?
The rigor with which composites designers and fabricators approach manufacture of parts and structures for aerospace and automotive applications is apparently not being employed in the production of some sporting goods parts, leading to product failure and, in some cases, injury and death. That’s the contention of Dr. Scott Beckwith, principal of BTG Composites (Taylorsville, UT, US), who offered a review at CAMX 2015 (Oct. 26-29, Dallas, TX, US) of his analysis of evidence in several product liability cases that involved carbon fiber bicycle forks and carbon fiber arrows.
Beckwith, who says he has testi- fied, to date, in 25-30 civil suits involving failure of advanced carbon fiber composites in either bicycles or arrows, has found in many cases that manufacturers fail to perform fundamental structural design analysis, design allowables studies, materials allowables studies, process optimization, as-built product testing and/or rigorous and ongoing quality control. This failure, he contends, spans many manufacturers in many countries and cannot be isolated to one brand or facility or manufacturing process.
“There is, in many cases, a complete lack of good design, analysis and manufacturing optimization practices,” he argues, compounded in many instances by a desire to manufacture parts quickly for large production quantities, which leads, he contends, to manufacturing shortcuts that cause significant flaws.
He says he has found in many of these litigated composite products, excess moisture in molding processes, loss of pressure, loss of vacuum, temperature deviations, foreign object debris and other problems. The effect on product quality is elevated poros- ity (some as high as 15%), delamina- tions, wavy fibers, resin-rich regions, resin-starved regions and fiber movement.
The most significant product fail- ures, Beckwith says, involve product flaws that lead to failure of a bike fork at speeds, often under 32 kph, that in almost all cases causes head or upper-body trauma severe enough to maim or kill the cyclist. Beckwith says correcting these design and manufacturing problems is not difficult, and he points to easily accessed ASTM D-30 stan- dards, which outline good, basic principles of determining composite materi- als allowables generation, process optimization, as-built product testing and product lot testing.
The question, from the audience, was how bicycle manufacturers might be incentivized to improve their manufacturing operations to help ensure product quality. Beckwith says he hopes that the industry will correct itself, but given the liability insurance some manufacturers carry, he fears that injuries from product failure might just be “the cost of doing business.”