The Design for Additive Manufacturing of Compliant Mechanisms for Application in the Aviation Industry

Abstract

The need for weight and cost reduction of parts while retaining efficiency and is widely desired in industry, especially in aviation. This thesis aims to add value to the aviation industry by combining additive manufacturing technologies and compliant mechanism design. This approach is considered to improve part consolidation in an airplane wing by reducing the number of moving parts and replacing them with suitable compliant mechanisms and flexures. This thesis aims to explain the benefits of these technologies and design by producing an airplane wing ‘slice’ and investigating the viability of application in the real world. Literature is reviewed to obtain a suitable additive manufacturing technology that is capable of rapid prototyping, the material is able to be compliant, and produce flexible but durable parts. Nylon-12 SLS (selective laser sintering) is chosen as the technology of powder bed fusion presents many benefits such as the low cost, no support material needed and the ability to produce durable, flexible, and highly precise parts. Further literature is reviewed to understand the design process and manufacture of compliant mechanisms, also which types of compliant mechanisms are required for the specific movement expected in an airplane wing. Initial concept design and testing is done to provide a base level of material knowledge when subjecting nylon-12 to flexible motion, this is then used to design and create various compliant flexures. The compliant flexures are then experimented to determine which movements are valuable to the design of the morphing wing slice. The rotary pivot was proven to be the most valuable flexure in terms of movement range given the relatively small size of the flexures. The results from the flexure and material testing provided the ability to design two different compliant wing slices. These were both experimented with different configurations of actuation force and the results were recorded and compared. The wing design that incorporated a moving rotary flexure skeleton with rotating hinges was proven to be the most valuable with a great range of motion and flexibility. This experiment proved the viability of compliant mechanism design and additive manufacturing technology to produce an airplane wing slice that is able to change an aerofoil shape mid use. Further research and testing will be required to incorporate the actuation force inside of the wing design that was unable to be done in this thesis due to the size of the servo motors available and the limitations of the SLS print bed size. A suitable exterior material would need to be researched as nylon- 12 is porous and not suitable for wet conditions. The wing designs and movement configurations would then need to be tested for their aerodynamic value and adjusted for precision.