Browse Topic: Wheels
Electric Vertical Takeoff and Landing (eVTOL) aircraft present a series of challenges to traditional aviation infrastructure that was designed for conventional rotorcraft. Questions have arisen within the vertical flight community as to the validity and applicability of applying current heliport markings and symbology to vertiports. Several of these questions were addressed in a previous paper from VFS Forum 80: "A Comparison of Proposed Concepts for Vertiport Markings and Symbology" (Ref. 6). In contrast, this paper extends that work and presents the results of additional research to enhance the visibility of the Federal Aviation Administration’s (FAA) “Broken Wheel” symbology. These notional enhancements to the "Broken Wheel" symbology were evaluated over the course of an experimental study using helicopter-rated pilots in the FAA William J. Hughes Technical Center’s S76-D and Loft Dynamics H125 and R22 rotorcraft flight simulators.
This SAE Recommended Practice provides minimum performance target and uniform laboratory procedures for fatigue testing of wheels and demountable rims intended for normal highway use on trucks, buses, truck-trailers, and multipurpose vehicles. Users may establish design criteria exceeding the minimum performance target for added confidence in a design. The cycle target noted in Tables 1 and 2 are based on Weibull statistics using two parameter, median ranks, 50% confidence level and 90% reliability, and beta equal to two, typically noted as B10C50. For other wheels intended for normal highway use and temporary use on passenger cars, light trucks, and multipurpose vehicles, refer to SAE J328. For wheels used on trailers drawn by passenger cars, light trucks, or multipurpose vehicles, refer to SAE J1204. For bolt together military wheels, refer to SAE J1992. This document does not cover other special application wheels and rims.
This SAE standard presents the basic information required for the design and manufacture of a wheel chock.
Gear design changes impact on gear crack propagation trajectory is investigated through numerical study. General purpose linear elastic fracture mechanics software, FRANC2D and FRANC3D, are used to simulate 2D and 3D gear crack propagation. FRANC can model non-planner, arbitrary shape crack surface for crack tip stress distributions, stress intensity factors, and crack propagation analyses. Maximum tensile stress and NASGRO4 fatigue crack growth models are employed to predict crack propagation direction and life. Three-dimensional idler gear crack propagation simulation shows the predicted crack trajectory is close to the field observation. Various 2D models are simulated to investigate the crack trajectory impact factors and design strategies to prevent gear rim failure. As shown in previous studies, the initial crack position and orientation play pivot role to control gear failure mode - tooth or rim. For a fixed crack position, this study shows the ratio between bend stress and
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