Trevor Collins

Bio: Trevor Collins is an academic researcher from Virginia Tech. The author has contributed to research in topics: Drop test & Takeoff. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Constrained Layer Damping Test Results for Aircraft Landing Gear

Abstract: In aircraft, weight reduction represents one of the principal design goals, and landing gear design is no exception. Accounting for 3 – 7% of an aircraft’s weight, the landing gear is essentially dead weight after takeoff, and so reducing this weight becomes a priority of aircraft design. In addition to keeping the weight low, fixed gear designs can add significant drag if the design has not been optimized. The ideal landing gear should be low weight and low drag, but these criteria are typically at odds with a requirement for absorbing landing loads and preventing rebound. The use of constrained layer visco-elastic damping on landing gear structural members is a new application since historic use of constrained layer damping has been found on thin plate-like structures. Benefits of low weight and low drag are achievable using the conformal treatment, and this paper investigates specific constrained layer damping applications for cantilever-loaded spring steel landing gear. The design of the damped system considers the high stiffness and low surface area typical on a cantilever landing gear leg. Damping levels are examined for a 163 kg. aircraft with and without a Dyad 606 constrained layer damping treatment on the main and nose gear members. A 29% increase in damping was observed on the main landing gear, and a 25% increase in damping was observed on the nose gear when the treatment was applied. A full aircraft drop test is performed that showed inconclusive results in damping.

Hybrid hollow microlattices with unique combination of stiffness and damping

Abstract: Hybrid micro-architected materials with unique combinations of high stiffness, high damping, and low density are presented. We demonstrate a scalable manufacturing process to fabricate hollow microlattices with a sandwich wall architecture comprising an elastomeric core and metallic skins. In this configuration, the metallic skins provide stiffness and strength, whereas the elastomeric core provides constrained-layer damping. This damping mechanism is effective under any strain amplitude, and at any relative density, in stark contrast with the structural damping mechanism exhibited by ultralight metallic or ceramic architected materials, which requires large strain and densities lower than a fraction of a percent. We present an analytical model for stiffness and constrained-layer damping of hybrid hollow microlattices, and verify it with finite elements simulations and experimental measurements. Subsequently, this model is adopted in optimal design studies to identify hybrid microlattice geometries which provide ideal combinations of high stiffness and damping and low density. Finally, a previously derived analytical model for structural damping of ultralight metallic microlattices is extended to hybrid lattices and used to show that ultralight hybrid designs are more efficient than purely metallic ones. [DOI: 10.1115/1.4038672]

A Simplified Flexible Multibody Dynamics for a Main Landing Gear with Flexible Leaf Spring

Abstract: The dynamics of multibody systems with deformable components has been a subject of interest in many different fields such as machine design and aerospace. Traditional rigid-flexible systems often take a lot of computer resources to get accurate results. Accuracy and efficiency of computation have been the focus of this research in satisfying the coupling of rigid body and flex body. The method is based on modal analysis and linear theory of elastodynamics: reduced modal datum was used to describe the elastic deformation which was a linear approximate of the flexible part. Then rigid-flexible multibody system was built and the highly nonlinearity of the mass matrix caused by the limited rotation of the deformation part was approximated using the linear theory of elastodynamics. The above methods were used to establish the drop system of the leaf spring type landing gear of a small UAV. Comparisons of the drop test and simulation were applied. Results show that the errors caused by the linear approximation are acceptable, and the simulation process is fast and stable.