Measuring the compression force on shoe soles

Customer’s needs and challenges

In the field of the shoe manufacturing, the transmission of the impact force is a central topic.

In order to reduce the transmitted vibrations through the bones and which are not controlled by the muscles and the tendons, it is essential to provide soles with a good cushioning ability. It limits the pain in the articulations and the degeneration of the cartilages through the reinforcement of the natural damping mechanisms.

As part of the development of soles for running shoes, the dissipation of shocks and the repartition of pressures are even more determinant as the duration and the intensity of the efforts are more important during sporting activities.

To control the damping capacity of shoe soles is an indispensable point as part of the R&D and the quality control.  Our client made use of the experience of Andilog to measure the force at a given displacement on certain parts of his soles.

Andilog’s solution for the verification of shoe soles

In order to answer the needs of our client, we´ve offered a universal and computer controlled test machine Stentor II CC, equipped with a load cell of 1.000 N and a compression platen of ø50 mm.

The company wanted to visualize in real time the curve of Force Vs. Displacement with a high resolution and save its test curves in order to analyze them subsequently. For this, we offered the test software Califort which enables to control the test stand with sequences and a precise follow-up of the force and displacement values.

Description of the test protocol

The load cell is mounted on the measuring head of the machine thanks to its thread. The compression platen is then inserted in the thread of the sensor. In Califort, we indicate the sequences for the displacement and the stop conditions and then go to the test menu.

The test protocol has been defined as follows to measure the compression force on soles:

• With a simple mouse click on the start button of Califort, the test stand goes down on the sole until it reaches a pre-defined force of 1 N.
• It performs a tare of the force and the displacement
• Then, a pre-load is applied on the sample at a speed of 100mm/min for a distance of 10 mm into the sole and comes back to its starting position, 0 mm
• The data saving starts at this point and the measuring head performs the latest operation over 4 cycles in order to enable a precise comparison of the different values
• At the end of the measurement, the measuring head goes back to the initial position and Califort save automatically the results, which are available in the menu «Analysis»

Key added values of this system

The Stentor II CC which has been selected for this project enables a precise force measurement with a precision of 0,1% of the total load cell capacity. Thanks to its included software Califort, it displays the curve Force Vs. Displacement in real time with a sampling rate of 1 000 Hz and up to 4 automatic calculations. Its programing sequence by sequence facilitates the measurements and enables to obtain repeatable results. Finally, the editing interface with personalized test reports ensures an unequalled traceability of your measurements.

Precise measurements on the long run

As for every measuring system, the Stentor II CC distorts over time and depending of the applied forces on the column. In order to compensate these deformations, Andilog created compensation profiles to adjust the displacement sensor and thus ensure the precision of your measurement on the long run.