Aerospace engineers need to compare potential designs for composite structures in terms of total weight and Design For Manufacturability (DFM). There are trade-offs. For example, composite structures with more panel-to-panel size variations weigh less but are more difficult – and therefore more expensive – to manufacture. Conversely, composite structures with fewer panel-to-panel size variations weigh more but are easier and less expensive to produce.
Today, Computer-Aided Engineering (CAE) software, such as HyperX® from Collier Aerospace, can optimise the lightest weight combination of material systems and panel cross-sectional dimensions. What aerospace engineers also need, however, is a way to see all the possible designs with a positive margin of safety, and an interface that lets them compare these options effectively. The company’s HyperXpert® tool was developed for this purpose.
Traditional CAE applications do not allow for design space exploration as they provide just a single data point that does not facilitate robust design comparisons. There are other limitations as well. For example, CAE software that is not aerospace-specific may not be able to generate a stress report for a preliminary and critical design review. Yet engineers are required to provide regulators with margin-of-safety calculations for airframe certifications.
HyperX® and HyperXpert® from Collier Aerospace:
Collier Aerospace, based in Newport News, Virginia, is solving these and many other challenges. Its HyperX® software uses Finite Element Analysis (FEA) results to perform sizing optimisation and, in turn, determine the lightest weight combination of materials and panel cross-sectional dimensions, including layup ply angles and stacking sequences. This allows engineers to quickly analyse design alternatives and consider trade-offs.
The HyperX® software optimises composite structure designs without requiring engineers to replace their existing tools. The software’s database establishes a digital thread and works with popular FEA and Computer-Aided Design (CAD) software such as Nastran, Abaqus, Optistruct, HyperMesh, Catia, 3DX and NX CAD. With the HyperX software, engineers can see the lightest weight design for all panels, load cases and failure criteria and without having to resubmit the FEA.
HyperXpert, a tool that extends the HyperX workflow, can perform a full factorial Design Of Experiments (DOE) and displays the best options for the design space in a weight-versus-size variation plot. Unlike other approaches to experimental design, the full factorial DOE tool analyses every combination of variables and determines the individual impact of each. This enables an engineer to decide which variables to link and determine how variables affect each other.
Because the DOE tool organises data in a plot, engineers can quickly compare results, review trends and select the best design to manufacture. By quantifying objective manufacturability considerations during the earliest conceptual design phases, users can also avoid unnecessary costs and accelerate project timetables. Importantly, they can increase their confidence in making design choices by seeing all their options.
Here are 2 case studies that explain how innovative companies are using these advanced software solutions to design light and cost-effective composite structures.
Swift engineering and the X-59 nose cone:
Swift Engineering of San Clemente, California, designs and builds high-performance aerospace vehicles. Recent projects include the extended nose cone for the X-59, an experimental aircraft from Lockheed Martin Skunk Works®, part of the Quiet Supersonic Technology (Quesst) mission within the US National Aeronautics and Space Administration (NASA). The goal of Quesst’s mission is to establish an acceptable noise standard for commercial supersonic flights over land.
For decades, regulators have banned these flights because they produce sonic booms, a sound associated with shock waves that are created when an object travels through air faster than the speed of sound. These intense noises can reach up to approximately 194 decibels (dB) and damage physical structures. Aircraft weight is a factor in sonic boom generation and intensity, but the X-59’s nose cone must also divert air flow and provide controlled aerodynamic pressure distribution to mitigate shock waves.
The 400-lb preliminary design specified a graphite/epoxy composite and a honeycomb-core sandwich structure. Swift Engineering used HyperX® software to remove unnecessary piles while optimising the design for stress and stability. Ultimately, the company reduced the nose cone’s weight by more than 25% to 300 lbs. With its unique geometry, the X-59 is expected to generate a barely audible thump instead of a sonic boom, and the elongated nose cone design is an important part of the solution.
In addition to designing and building this composite structure, Swift Engineering was tasked with performing structural analysis and certification testing. The company was also responsible for evaluating a wide range of load cases and providing detailed stress reporting for part release and fabrication. By using the full capabilities of Collier Aerospace’s software, Swift Engineering completed the project’s requirements and delivered the X-59’s nose cone ahead of schedule and under budget.
Radia and the WindRunner™ cargo aircraft:
Radia is an aerospace manufacturing company based in Boulder, Colorado, that is building the world’s largest aircraft, the WindRunner™, to deliver wind turbines with blades up to 100 m (330 ft) in length to onshore wind farms, avoiding the limits of ground transportation. To develop this unique aerial transportation solution, Radia sought assistance from Collier Aerospace at an early stage as both a software provider and engineering consultant.
Radia used Collier Aerospace’s methodology for structural sizing and analysis and conducted configuration assessments of the wings, fuselage, ribs, spars, stringers and many other parts, which will be made of both composite material and metal. The aerospace company also leveraged the automated sizing capabilities in the HyperX® software to account for unusual variables such as the huge size and capacity of the unpressurised fuselage. This enabled Radia to make significant progress quickly.
In accelerating the engineering cycle and shortening the certification processes from the US Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA), Radia is also concurrently removing weight and costs from composite structures. The company also plans to use software from Collier Aerospace to validate work performed by suppliers that will handle structuring sizing in the detailed design phase.
New heights and the right tools
Like Swift Engineering, Radia is reaching new heights with the right tools. HyperX® software from Collier Aerospace identifies the lightest material and panel configurations, including ply angles and stacking sequences, so that aerospace engineers can evaluate design trade-offs efficiently. HyperXpert® enhances the design process by evaluating all variable combinations, enabling engineers to understand and visualise the impact of each factor on the design of composite structures.
By supporting faster and more informed decision-making, these software solutions are also advancing regulatory compliance and Design For Manufacturability (DFM). As companies like Swift Engineering and Radia use Collier Aerospace’s software to optimise their designs without replacing their existing tools and without having to resubmit the FEA, aerospace engineers can design lighter and less expensive composite structures more efficiently.
source: Collier Aerospace /JEC Composites
