To date, topology optimization has proven to be the most beneficial, yet most complex, structural optimization technique available to engineers and scientists. However, particularly in the aerospace industry, there exists little application to real-world design problems, including all the complexities required to ensure that the resulting design complies with the regulations. In this paper, a topology optimization algorithm is developed to solve aerospace design problems. Two problems are considered in this work. The first is the design of an aircraft landing gear. The final topology is compared to a design found using standard engineering practices to show the benefits of topology optimization. The second problem uses the topology optimization methodology to design an aircraft engine mount. The main goal of this paper is to demonstrate that topology optimization can be used to find minimum weight structures to aerospace design problems, using Federal Aviation Regulations to ensure that the resulting designs meet the airworthiness standards of the aviation industry.

On the benefits of applying topology optimization to structural design of aircraft components

This paper proposes a novel fully probabilistic framework for the performance‐based seismic design of structures and uses tuned inerter dampers (TID) installed in civil engineering structures subjected to seismic loads to illustrate its applicability. The framework proposed is based on stochastic reduced‐order models, which makes it computationally efficient and can be used for the design of TIDs installed in any complex nonlinear structures subjected to general nonstationary, non‐Gaussian stochastic processes. In this study, the TID is installed in a multi‐degree‐of‐freedom nonlinear structure that is subjected to synthetic seismic records. Numerical results show that the framework proposed is able to provide rigorous and robust values for the parameters of the TID. The design parameters obtained using the stochastic framework proposed are compared with benchmark deterministic approaches, tested also for a large data set of ground‐motion real records. It is shown that the stochastic approach provides insightful designs of the TID that are consistent with the site seismicity and the frequency content of the stochastic excitation.

/pdf/performance-based-seismic-design-of-tuned-inerter-dampers-2uec1uvyxy.pdf

Performance-Based Seismic Design of Tuned-Inerter Dampers

This paper describes airfield measurement of forces and moments that act on a landing gear wheel. For the measurement, a wheel force sensor was used. The sensor was designed and built based on strain gage technology and was embedded in the left landing gear wheel of a test aircraft. The sensor is capable of measuring simultaneously three perpendicular forces and three moments and sends data to a handheld device wirelessly. For the airfield tests, the sensor was installed on a PZL 104 Wilga 35A multipurpose aircraft. The aircraft was towed at a "marching man" speed and the measurements were performed at three driving modes: Free rolling, braking, and turning. The paper contains results obtained in the field measurements performed on a grassy runway of the Rzeszow Jasionka Aerodrome, Poland. Rolling resistance of aircraft tire, braking friction, as well as aligning moment were analyzed and discussed with respect to surface conditions.

https://www.mdpi.com/1424-8220/20/1/227/pdf

Determining Wheel Forces and Moments on Aircraft Landing Gear with a Dynamometer Sensor.

A power-by-wire aircraft brake system based on high-speed on-off valves

The landing gear retraction system of an aircraft, including mechanical and hydraulic systems, is complex and nonlinear. It has many uncertain factors, which lead to difficulty in reliability analysis. To make the reliability analysis more accurate and efficient, some studies are represented in this paper. Taking the main landing gear of an aircraft as a research object, the dynamic equations of the retraction system were derived. The simulation model was built, combining the mechanism dynamics with the hydraulic system, and its accuracy was verified by laboratory test results. Based on this model, the paper shows how the key parameters, including the crosswind velocity, the diameter of the damping orifice, liquid capacity, friction, and oil leak, affect the performance of the landing gear retraction. After that, the limit state equation of the retraction system’s reliability was set up. For the implicit limit state equation, the response surface model of retraction reliability was established with a quad...

Reliability Analysis of Landing Gear Retraction System Influenced by Multifactors

https://research-information.bris.ac.uk/files/195221173/Investigation_of_gear_walk_suppression_while_maintaining_braking_performance.pdf

Investigation of gear walk suppression while maintaining braking performance in a main landing gear

Improved Model of Landing-Gear Drop Dynamics

Nomenclature Aa = pneumatic area Ah = hydraulic area Ao = area of opening in orifice plate Ap = cross-sectional area of metering pin or rod in plane of orifice A0 = net orifice area Cd = orifice discharge coefficient d = damping coefficient of supporting damper Fa = pneumatic force in shock strut FC = damping force applied on the floating mass Fh = hydraulic force in shock strut FK = spring force applied on the floating mass FS = total axial shock-strut force FVa = vertical force, applied at axle FVg = vertical force, applied to tire at ground g = gravitational constant h = bulge height (height of upper surface of floating mass over runway) KL = lift factor, L/w k = stiffness of supporting spring L = lift force m, r = constants corresponding to the various regimes of the tire-deflection process n = polytropic exponent for air-compression process in shock strut pa0 = air pressure in upper chamber of shock strut at zero stroke ph = hydraulic pressure in lower chamber of shock strut rd = radius of deflected tire s = shock-strut axial stroke v0 = air volume of shock strut at zero stroke w = total dropping weight w1 = weight of upper mass above strut w2 = weight of lower mass below strut w3 = weight of floating mass z1 = vertical displacement of upper mass from position at initial contact

Dynamic Analysis of Aircraft Landing Impact Using Landing-Region-Based Model

The invention provides a plane type ejection launch carrier-borne aircraft front undercarriage static force test loading apparatus. The apparatus comprises a plane type test bench rack, an undercarriage, a lateral load loading device, a course load loading device, a vertical load loading device, an ejection load loading device, a hamper load loading device and a mooring load loading device. Based on a conventional loading technology, a set of loading equipment capable of applying ejecting, hampering and mooring loads is designed, and the vertical, course, lateral, ejection, hampering and mooring load loading of an ejection launch carrier-borne aircraft is finished on a single test bench, no replacement of tools is needed, all the loading points are fixed in the frame type test bench, a self-balance bearing system is formed when loading is performed, the bearing of the test bench is quite small, the fixation is facilitated, and the precision is high.

Plane type ejection launch carrier-borne aircraft front undercarriage static force test loading apparatus

The bifurcation analysis method is used to study the high-speed unmanned aerial vehicle (UAV) dynamics and directional stability during the steering process on the ground. A UAV nonlinear ground ta...

Dynamics and Directional Stability of High-Speed Unmanned Aerial Vehicle Ground Taxiing Process

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