Mann N A, Griffin M J
Human Factors Research Unit, University of Southampton, England.
Cent Eur J Public Health. 1996 Feb;4(1):46-9.
The influence of physical factors on the mechanical impedance at the palmar surface of the finger have been investigated. The studies were conducted with 12 subjects using random vibration over the frequency range 10 to 1000 Hz. It was found that increase in contact force (from 0.25 to 8 N) caused large increases in the modulus of the point mechanical impedance over most of the frequency range, increasing the area of contact with the finger (from 12.6 mm2 to 78.5 mm2) increased impedance at frequencies below 100 Hz and above 400 Hz. The location of contact with the finger also influenced the measured mechanical impedance. The resonance frequency increased from about 30 Hz, when vibration was applied to the proximal phalanx, to 600 Hz when vibration was applied to the distal phalanx. The addition of mass to the fingernail (0.5 to 8 g) reduced the resonance frequency from 700 Hz to 180 Hz and caused increased magnitudes of impedance at resonance by about a factor of 3. Flexing the finger affected impedance at frequencies between 50 and 200 Hz. The results show that the transmission of vibration to the fingers, and therefore the effects of vibration on the fingers, are highly dependent on some aspects of the contact between the fingers and the source of excitation. These variables are not currently quantified when assessing the severity of tool vibration, yet their optimisation may help to minimise some of the adverse effects of hand transmitted vibration.
研究了物理因素对手指掌面机械阻抗的影响。对12名受试者进行了研究，在10至1000Hz频率范围内施加随机振动。结果发现，接触力增加（从0.25N增加到8N）会导致在大部分频率范围内点机械阻抗的模量大幅增加；手指接触面积增加（从12.6平方毫米增加到78.5平方毫米）会使100Hz以下和400Hz以上频率的阻抗增加。与手指的接触位置也会影响测量到的机械阻抗。当振动施加于近端指骨时，共振频率约为30Hz，而当振动施加于远端指骨时，共振频率为600Hz。在指甲上增加质量（0.5g至8g）会使共振频率从700Hz降低到180Hz，并使共振时的阻抗幅值增加约3倍。手指弯曲会影响50至200Hz频率范围内的阻抗。结果表明，振动向手指的传递以及因此振动对手指的影响，高度依赖于手指与激励源之间接触的某些方面。在评估工具振动的严重程度时，这些变量目前尚未量化，然而对它们进行优化可能有助于将手部传递振动的一些不利影响降至最低。
