Ultra-light weight design through additive manufacturing

Abstract: ABB Corporate Research was looking to redevelop one product to be manufactured via polymer additive manufacturing (AM), as opposed to its previously traditionally manufacturing method. The current product is cylindrical in shape and must withstand a certain amount of hydrostatic pressure. Due to the pressure and the current design, the cannister is prone to buckling failure. The cannister is currently produced from two cylindrical tube parts and two spherical end sections produced from solid blocks of the same material. For assembly, an inner assembly is inserted into one of the tube parts and then all parts are welded together. This product is also custom dimensioned for each purchase order. The purpose of investigating this redevelopment for AM is to analyse if an updated inner design unique to additive manufacturing is able to increase the performance of the product by increasing the pressure it can withstand from both a material failure standpoint and a buckling failure. The redevelopment also aims to see if the component count and process count can be decreased. Ultimately, two product solutions are suggested, one for low pressure ranges constructed in ABS and one for high pressure ranges constructed in Ultem 1010. To accomplish this, relevant literature was referred to gain insight into how to reinforce cylindrical shell structures against buckling. Design aspects unique to AM were also explored. Iterations of these two areas were designed and analysed, which led to a final design choice being decided upon. The final design is ultimately based on the theory of strengthening cylindrical structures against buckling through the use of ring stiffeners while also incorporating AM unique design aspects in the form of hollow network structures. By utilizing finite element analysis, the design was further developed until it held the pressure required. Simulation results suggest that the ABS product can withstand 3 times higher pressure than the original design while being protected against failure due to buckling. The Ultem simulation results suggest that the product can withstand 12 times higher pressure than the current design while also being protected against failure due to buckling. Part count and manufacturing processes are also found to have decreased by half. Post-processing treatments were also explored, such as the performance of sealants under pressure and the effects of sealants on material mechanical properties. Results show that one sealant in particular, an acrylic spray, is most suitable to sealing the ABS product. It withstood a pressure of 8 bar during tests. The flexural tests showed that the sealant did indeed increase certain mechanical properties, the yield strength, however did not affect the flexural modulus significantly. This work gives a clear indication that the performance of this product is feasibly increased significantly from redeveloping it specifically to AM.