Areal Surface Characterization of Involute Gears with Microgeometry Corrections and Contact Fatigue Damage for Tooth Contact Analysis

Reavie, T; Frazer, R; Lambert, R; Wilson, S; Pourmohammadi, N; Aylott, C; Shaw, B

Areal Surface Characterization of Involute Gears with Microgeometry Corrections and Contact Fatigue Damage for Tooth Contact Analysis

Lookup NU author(s): Tom Reavie ORCiD, Dr Robert Frazer ORCiD, Robert Lambert, Stephen Wilson, Navid Pourmohammadi, Christopher Aylott, Professor Brian Shaw

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Abstract

Characterizing the surface geometry of involute gears is crucial for many high-performance applications and when innovative machining and finishing processes are used. While traditional line (1D) measurements are well-defined by international standards, guidelines for gear surface measurement are currently not available. Despite this, surface measurements have been performed in industry and explored in literature over the past decade.The National Gear Metrology Laboratory (NGML) at Newcastle University have recently developed an involute gear surface characterization capability. The evaluation strategy implements Ni and Goch’s proposed areal extension of traditional parameters by fitting Chebyshev polynomials. NGML developed a method to estimate the measurement uncertainty of the characterization parameters using traceable and calibrated 1D helix and profile measurements. The method also quantifies microgeometry corrections such as tip relief, root relief, and end relief.To demonstrate the method's applicability, contact fatigue test gears were analyzed to quantify micropitting and compared to current damage evaluation methods used by the Design Unit at Newcastle University.Measurements were conducted using a tactile probe on a Klingelnberg P65 gear measurement machine. Contact stress and transmission error were simulated in Dontyne Systems 3D FEA based tooth contact analysis model. Surfaces with no or nominal modifications, as-manufactured surfaces, and subsequently damaged surfaces were analyzed and are discussed.Future work and other potential applications will be discussed including quantifying surface run-in effects, coatings, micropitting progression, and other gear performance standards and model validation.