Numerical and experimental testing of aircraft tyre impact during landing

The capability of aircraft tyres to sustain landing impact loads is essential for flight landing safety. Hence, the development of a reliable experimental database is necessary to validate numerical models. The experimental data on aircraft tyre landing impact in the public literature are somewhat sparse. This paper describes a detailed design rig for aircraft tyre impact testing. A finite element model is then created and simulated using a finite element tool (ABAQUS). Inflation and static load simulations are analysed based on the FE tyre model to confirm its reliability. Comparison of experimental measurements with the results reveals that the model can predict the significant features of aircraft tyre impact in a landing scenario. Very little experimental data are publicly available to verify aircraft tyre models. Therefore, the experimental data in this paper fill this gap in the literature.

Parametric Analysis on Landing Gear Strut Friction of Light Aircraft for Touchdown Performance

The aim of this paper is to obtain the strut friction–touchdown performance relation for designing the parameters involving the strut friction of the landing gear in a light aircraft. The numerical model of the landing gear is validated by drop test of single half-axle landing gear, which is used to obtain the energy absorption properties of strut friction in the landing process. Parametric studies are conducted using the response surface method. Based on the design of the experiment results and response surface functions, the sensitivity analysis of the design variables is implemented. Furthermore, a multi-objective optimization is carried out for good touchdown performance. The results show that the proportion of energy absorption of friction load accounts for more than 35% of the total landing impact energy. The response surface model characterizes well for the landing response, with a minimum fitting accuracy of 99.52%. The most sensitive variables for the four landing responses are the lower bearing width and the wheel moment of inertia. Moreover, the max overloading of sprung mass in LC-1 decreases by 4.84% after design optimization, which illustrates that the method of analysis and optimization on the strut friction of landing gear is efficient for improving the aircraft touchdown performance.

Friction analysis of aircraft landing gears due to landing impact

In this work, a six degrees of freedom heave-pitch mathematical model has been developed for an aircraft with main and nose oleo-pneumatic landing gear. Nonlinearities in stiffness, damping, and bending characteristics of landing gears and tires are incorporated in the model. Friction is an incidental and inevitable reaction that sticks along with the strut motion during the event of ground contact. The friction generated in the landing gear is the sum of the contribution from bearings and seals fitted in the landing gear. This study has focused on investigating the amount of frictional resistance gained by the struts while an aircraft is landing at various sink rates. The strut vertical forces, seal friction forces, and bearing friction forces generated in the main and nose landing gear during touchdown have been presented in this work. This preliminary estimation of friction forces for a range of sink rates aids the designer in developing optimal geometric or strut parameters in the design stage. This work also helps to calculate total landing loads for the certification of the landing gear.

Analysis and Ethical Design of Terrain Park Jumps for Snow Sports

Most American snowsport resorts now have terrain parks and decades-long epidemiological evidence correlates terrain park use with injuries. Engineering design of jumps could reduce injuries by limiting equivalent fall heights (EFHs), which indicate dissipated landing impact energy. No evidence refutes making terrain park jumps safer in this way. We discuss case studies illustrating that large EFHs are significant factors in traumatic injuries on terrain park jumps. Standards and design tools for builders can make jumps safer. We introduce a tool that can evaluate existing jumps as well as design jump profiles with safer equivalent EFHs to reduce injuries.

Using the VERT wearable device to monitor jumping loads in elite volleyball athletes

Sport is becoming increasingly competitive and athletes are being exposed to greater physical demands, leaving them prone to injuries. Monitoring athletes with the use of wearable technology could provide a way to potentially manage training and competition loads and reduce injuries. One such technology is the VERT inertial measurement unit, a commercially available discrete wearable device containing a 3-axis accelerometer, 3-axis gyroscope and 3-axis magnetometer. Some of the main measurement outputs include jump count, jump height and landing impacts. While several studies have examined the accuracy of the VERT’s measures of jump height and jump count, landing impact force has not yet been investigated. The objective of this research study was to explore the validity of the VERT landing impact values. We hypothesized that the absolute peak VERT acceleration values during a jump-land cycle would fall within 10% of the peak acceleration values derived simultaneously from a research-grade accelerometer (Shimmer). Fourteen elite university-level volleyball players each performed 10 jumps while wearing both devices simultaneously. The results showed that VERT peak accelerations were variable (limits of agreement of -84.13% and 52.37%) and had a propensity to be lower (mean bias of -15.88%) when compared to the Shimmer. In conclusion, the validity of the VERT device’s landing impact values are generally poor, when compared to the Shimmer.

Research on the nose landing gear of a military training aircraft

This paper presents the analysis of the landing gear configurations and the proposal of a solution for a military training aircraft. The paper presents both landing gears: nose and main because they are inextricably linked. The nose landing gear of military aircraft is a complex system composed of structural elements, electric and hydraulic components, energy absorption components, aircraft tire wheels etc., which is dimensioned according to the weight of the aircraft. Additional components attached to the nose landing gear include a landing gear extension and retraction mechanism and a steering system. The landing gear must withstand the weight of the aircraft in all phases of take-off (maximum weight: fuel, armament, ammunition, other equipment, flight crew etc.) and landing (impact from landing and a lower weight after completing the mission due to fuel consumption and ammunition use).

COMPARATIVE ANALYSIS OF METHODS FOR DETERMINING THE MASS OF THE SHAFT OF A SPORTS AND AEROBATIC AIRCRAFT, MADE OF TITANIUM AND COMPOSITE MATERIAL

Comparative analysis of an acrobatic aircraft's weight and shaft which is made of a titanium alloy and composite materials. The article contained requirements and specificities of an acrobatic aircraft's landing gear shaft design. The article describes prediction method of an acrobatic aircraft’s weight fraction of shaft which is allows to take into account shaft mass on wing loading upon condition that composite materials will be used in construction. Research objectives include: –Documentation of an acrobatic aircraft’s shaft design. – Analytic dependence conclusions on shaft mass by applying energy absorption of landing impact. – To quantify the algorithm of shaft mass based on strength prediction of shaft construction. –To quantify the mass and construction of shaft based on patterns that are made of titanium and composite materials. – Comparative analysis and references to practical using these methods to quantify shaft’s mass. –To quantify how shaft mass influenced by wing loading. –Designing shaft construction that is made of titanium alloy VT22 and composite material VKU26 by taking into account quantity and ply layup. Comparative analysis shaft mass which is made by different variety of composite materials. The constructive analysis is distinguished for decreasing the shaft mass that is made by composite material and references on ply layup.