Study of Biomechanical Response of Human Hand-Arm to Random Vibrations of Steering Wheel of Tractor

• 作者: C.Sujatha G.Geethanjali
• 来源期刊: 分子与细胞生物力学(英文)
• 学科: 数学
• 关键词: Hand-arm VIBRATION syndrome finite element modeling hand-transmittedvibrations DAILY VIBRATION exposure value
• 年，卷（期）: 2013,（4）
• 页码范围: 303-317
• 页数: 15页
• 分类号: O17

摘要

This paper reports a study on the biomechanical response of a humanhand-arm model to random vibrations of the steering wheel of a tractor. Ananatomically accurate bone-only hand-arm model from TurboSquidTM was used toobtain a finite element (FE) model to understand the Hand-arm vibration syndrome(HAVS), which is a neurological and vascular disorder caused by exposure of thehuman hand-arm to prolonged vibrations.Modal analysis has been done to find out the first few natural frequencies and modeshapes of the system. Coupling of degrees of freedom (DOF) had to be done in theFE idealization to do modal analysis, as the bones were not attached to each otherin the TurboSquidTMmodel. The shoulder bone, scapula, has been constrained atone end for eigenvalue analysis. It was observed that the first five natural frequencieswere in the range of 0-250 Hz, which is the range in which the effect of HAVSis the highest. Harmonic analysis was done by giving a swept sine excitation inthe frequency range 0 to 200 Hz. For this, a force input of 25 N was imparted atnodes perpendicular to the hand, the force value chosen being the nominal force inmost applications involving powered hand-held tools and steering wheels of tractors.The nodes chosen for force application were determined experimentally fromobservations made by gripping the steering wheel. The frequency response function(FRF) plots were obtained in the x, y and z directions.Random vibration analysis was done next by giving force power spectral densities(PSD) in the form of nodal excitation as input to the FE model of hand-arm, andcomputing the output acceleration PSDs. The input force PSDs were measuredusing FlexiForce? sensors along the three axes. The acceleration responses at thesteering wheel were also measured using tri-axial accelerometers for validating thecomputed results. The output acceleration PSDs were then weighted using the frequencyweighting curves for hand-arm vibration and the total daily exposure A(8),computed using ISO 5349-1 standards, was compared with