Shock-absorbing Effect Research Articles

The shock-absorbing effect of soles and insoles

The capacity of heel inserts of different plastic and rubber materials to attenuate heel-strike forces was analysed. The heel-strike response was recorded by accelerometers fastened on to the skin. Thirteen rheumatoid patients with a knee arthroplasty and five healthy controls were tested. Inlay material of 6 mm thickness did not significantly reduce the tibial deceleration produced by heel-strike. However, shoes with heels of polyurethane plastic of 20 mm thickness significantly lowered the amplitude of the tibial response compared with rubber-heeled shoes. The possible implications of this for patients with degenerative joint diseases or with joint implants is discussed.

Oleo Gears for Aircraft

Abstract After describing the various oil damping devices for reducing the landing shocks of airplanes, the author presents a theory and test data for the design of the “oleo” type of landing gear. This type depends on the flow of oil past an orifice for the shock-absorbing effect. Tests on several forms of orifice using different fluids under a steam hammer gave satisfactory orifice coefficients for design purposes. Then landing gears were dropped under weights with different combinations of orifice and needle, wheel, and tire through heights varying up to 42 in. and their performance studied in slow-motion pictures and cards from pressure indicators attached to the gears. In the plain oleo mechanism together with tire and wheel, it has been found that almost constant deceleration is obtained with no tapering needle in the oil orifice. Viscosity of oil medium has little effect.