There are many ways to evaluate sole comfort and pressure testing. There is one aspect that has not been deeply studied before, that is, the aging of shoes, especially the sole aging caused by repeated pressure. Heel impact on the ground, as well as the wearer’s body weight, can cause different pressure effects on the heel, which has never been completely replicated in the laboratory. CTC, a French testing organization, now has a special experiment to fill this gap. 1n the experiment, they use their own machine to measure sports shoes (running shoes, hiking shoes, basketball shoes, etc.), as well as men’s shoes and women’s shoes. The machine was designed to replicate the pressure on the back of the sole, which is caused by repeated bumps during walking or running. The results are displayed according to the type and condition of use (walking or running a specific length of distance, etc.), so that the results can be applied to manufacturers and consumers immediately
test principle
put a movable hinged last in the shoe, and use a hammer to simulate the pressure generated by the walker or runner under the pressure of 200000 cycles. At the end of the test, a degradation value is obtained, which represents the degradation degree of the heel
it is difficult to describe the movement state of walking or running completely. However, the principle of the test is to press the heel downward. According to the different process of the test, the repetition frequency is also different. Several biomechanical problems are involved in the test: 1. The pressure is applied to the talus through the tibia from 35mm away from the outermost part of the calcaneus. The hammer accurately falls from 35mm behind the last2. Pressure must be applied to the heel (where the foot hits the ground). Each hammer has a small piece of metal under it, and the heel of the tested shoe is attached to it. 3. The walking and running signals used must actually reproduce these behaviors. During walking, CTC uses a maximum voltage of 700n and a frequency of 1Hz. During running, the maximum pressure increases to 3000n, and the frequency increases t2.6hz. These values are consistent with the biomechanical data obtained in reality
test equipment
the machine is very simple, with two hydraulic hammers, independent hydraulic pumps and a thermostat controlled air cooling system. There is a control panel on the front to control the equipment, and there are pressure sensors to measure. The software selects the number of cycles based on the soles tested (walking shoes, running shoes, etc.) and the signals sent to the hammer. Two different shoes can be tested independently at the same time, because the pressure and frequency can be programmed separately and applied to different hammers and shoes. The device can be applied to size 37 to 43 shoes, which can be quickly and easily installed under the hammer, so that the test can be easily copied and repeated
the structure of the hammer is very special. When the shoe and last fall, they will return to the starting point to ensure that each blow is the same. The joint between the shoe last and the shoe last is exactly 35mm away from the heel, so that the applied pressure is consistent with the fact that the foot moves, and the pressure generated by the tibia is exactly 35mm away from the talus. The end of the hammer is equipped with a gasket to prevent the shoe from sliding to the side. The degradation value is given after 200000 cycles, and different values are given according to different machine settings for walking or running: 1. The minimum value of walking pressure is 50N, the maximum value is 700n, and the frequency is 1Hz (200000 cycles take more than 55 hours.2. The minimum running pressure setting is 50N, the maximum is 3000n, and the frequency i2.6hz (200000 cycles now only take a little more than 21 hours.)
results
the degradation value is calculated according to the minimum material pressure of the heel during compression. Corresponding to the minimum material pressure at the end and beginning of the test. The reference value is calculated from the 10th cycle strike, because the previous cycle is prone to error. The equipment provides a method for establishing a new standard of heel comfort and durability. Premature heel failure often means quality and aging problems. This factor also affects comfort, as it has a significant impact on the stability of the back of the shoe
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