Thermo-mechanical coupling and modal analysis of expansion slot designs for enhancing the dynamic stability of ultra-thin circular saw blades

Ultra-thin circular saw blades have become prevalent in contemporary woodworking owing to their superior material efficiency and cutting performance. Nonetheless, their thermo-mechanical stability under high-speed rotational settings continues to be a substantial limitation on precision machining efficacy. This study examines the interrelationship between the geometric design of thermal expansion slots and the behavior of multiphysics coupling. A comprehensive three-field coupled finite element model is developed, integrating cutting heat source loading, thermal stress progression, and centrifugal stress response. This model methodically assesses the control mechanisms of standard slot-type constructions for saw blade temperature distribution, modal response, and critical rotational speed. Simulation and experimental results reveal that the average temperatures for straight-line, symmetrical curved, and asymmetrical curved slots are 59.80 °C, 58.18 °C, and 57.60 °C, respectively. The asymmetrical curved slot markedly reduces local heat accumulation and thermal stress concentration. Thermal-mechanical coupled pre-stress modal analysis indicates critical rotational speeds of 6432 r/min, 6494 r/min, and 6537 r/min for the three slot types, as demonstrated by Campbell diagrams. The asymmetric curved slot design resulted in a 105 r/min enhancement compared to the straight slot, while offering over 5% frequency separation in the 2nd, 4th, and 6th nodal-diameter mode. This significantly improves modal separation and dynamic stability margin, mitigates coupled resonance concerns, and provides a broadly applicable theoretical foundation and engineering approach for enhancing the stability of ultra-thin circular saw blade constructions. • A 3D thermo-mechanical FE model is validated by infrared blade temperature tests. • Three expansion slot paths are compared: straight, symmetric and asymmetric curves. • Asymmetric curved slots lower tooth-root temperature by about 2.2 °C at 3000 rpm. • Asymmetric slots raise critical speed from 6432 to 6537 rpm and enlarge modal gaps.