Layout Optimization of Aerospace Components with Minimum Frequency Constraints Suitable for Additive Manufacturing

The art of aerospace engineering is producing the highest performing component whilst meeting: stringent rules on safety; material strength and temperature capabilities; component and product weight; frequency requirements; and meeting cost targets. Automated optimization techniques are necessary to ensure that the best product can be achieved to meet these criteria. Optimization tools have long been used, these have tended towards size and shape optimization, however the advent of high powered computing and modern manufacturing techniques has allowed generative design methods to come to the fore. Topology optimization is widely employed in the demonstration of optimization for engineering design, though it is not without its detractors. Truss layout optimization, familiar in the field of civil engineering, has been little used in aerospace.

This thesis looks at the optimization methods used in aerospace. A comparison is drawn between topology and truss layout optimization, following the end-to-end design process for each before drawing conclusions that both offer substantial weight savings but truss layout optimization does so in shorter timescales. A new bespoke tool for optimizing components using truss based layout optimization with constraints on natural frequency has been developed and its success is demonstrated via a diverse range of numerical examples. This is then extended to frame structures, which contain rigid joints and more closely represent an additively manufactured component. A second bespoke tool is presented to treat frame structures with frequency constraints and its capability is once again demonstrated via numerical examples.