Shock attenuation of running shoes

Shock attenuation of running shoes

Moltmaker, M.

Jansen, A.J. (mentor)
Jellema, A.H. (mentor)

Industrial Design Engineering

Industrial Design

2015-09-28

During the running activity impact with the ground causes the muscles of the runner to vibrate. Especially vibrations in the lower frequencies of around 10 Hz can be uncomfortable. Footwear can help to decrease muscle vibrations. Softer and more viscous shoes allow the muscles to come to rest at a later moment in time. However, the softness of the midsole material may not be a good indicator of comfort. The Cushioning Parameter (CP) gives an indication of how much of the lower frequencies are attenuated compared to an uncushioned situation. This parameter is in better accordance with the perceived level of comfort. It was found that the idea of using a metamaterial sole structure, consisting of buckling rods, can increase this Cushioning Parameter. A metamaterial shows varying behaviour due to its structure. In this case the rod’s dimensions are adjusted over the sole of the shoe. In the cushioning heel region the rods need to buckle earlier, while offering more stability in the toe region. By varying the density of the rods the structure may also counter running related effects like pronation. Next to that the required 3D printing of the structure also opens up possibilities for an improved supply chain, shopping experience and brand loyalty. However, the printing technology is still in development and needs improvements concerning the production costs, and most of all its material’s mechanical properties like tear strength. Tests and simulations were performed to check the validity of the claims made about the metamaterial structure. It was claimed, for example, that the Metamaterial concept shows an increased CP-value, compared to the current situation, due to spreading of the impact pressure and lowering of the loading rate. The tests and simulations showed that the metamaterial structure can indeed improve the pressure distribution and lower the loading rate. Therefore the structure is also likely to have an increased CP value. However, the CP value could not be determined within the timeframe of this project and the used material’s behaviour proved to be very complex. Its viscoelastic behaviour was very difficult to reliably simulate and its 3D printed nature meant the material’s behaviour changed with every compression. It is therefore recommended to further explore a TPU printing material, which is likelier to offer more consistent results and overall better material properties.

footwear
running
additive manufacturing
shock attenuation

http://resolver.tudelft.nl/uuid:539a2316-0c7e-4e44-b9cb-794f3a606c0e

2016-09-28

Campus only

Student theses

master thesis

(c) 2015 Moltmaker, M.