Fabrication of Compressed Hosiery and Measurement of its Pressure Characteristic Exerted on the Lower Limbs

Two different methods are used to measure the prior characteristics of compressed hosiery. As differences exist between the two methods, it is important to quantitatively analyze these differences. The compressed hosiery used for most studies is purchased from the market.

The material and structure of these hosieries are uncontrollable. We have fabricated the compressed hosiery samples ourselves. This method could also be used to measure other compression garments, such as compress pants and waistcoats.

We’re sure demonstration of this method will help viewer to better understand the method and our work. Demonstrating the procedure will be Jiecong Li and Qi Fang, the graduate students from my laboratory. To create a new sock construction, open the Atlas MP615 stocking software and select Plain Fabric.

Select DOUBLE WELT 1 FEED, Transfer without pattern, PLAIN MEDICAL LEG FROM DOUBLE WELT 1 FEED, BEGIN HEEL FROM PLAIN MEDICAL LEG, END OF HEEL AND PLAIN MEDICAL FOOT, BEGIN TOE FROM PLAIN FOOT 1F, PLAIN TOE WITH ROSSO AND CLIP, SOCK RELEASE WITHOUT TURNING DEVICE, and END OF SOCK. Then, click OK to complete the sock design. Select 200 for the needle and export the program file onto a USB flash disk.

Switch to Quasar to change the fabrication parameters and click any blue button in the GRADUATION row to open a new window. For fabricating the compressed hosiery with a different structure, enter 500 in the Cylinder S and E columns and click OK.Click any one of blue buttons in the ELASTIC MOTORS row and enter 800 in the WELT rows in the Cylinder S and E columns. In the MEDICAL LEG row, enter 800 in the S column and 650 in column E.Then, enter 650 in the ANKLE row in the S and E column and click OK to complete the setup.

To prepare the ground and elastane yarns on the compressed hosiery fabrication machine, turn on the machine, insert the USB drive, and select the compressed hosiery fabrication program file. The machine will automatically fabricate the compressed hosiery sample. When all of the samples have been acquired, condition the samples for 24 hours in a standard atmospheric environment.

The next day, place a sample onto an artificial lower limb and mark six evenly spaced circle lines on the compressed hosiery sample dressings from the knee to the ankle. These lines divide the compressed hosiery samples into five parts. To perform a pressure measurement, place the interface pressure sensors under part one of the compressed hosiery sample in the anterior, posterior, medial, and lateral directions.

Be sure to take care when placing the hosiery onto the artificial leg, as the sensor is very soft and may become folded and damaged during the dressing process. In the measurement software, select the appropriate serial port COM and set the minimum threshold value as zero. Click Start Measurement.

A one-to-four real-time channel will display the pressure data. When the pressure is stable, click Stop Measurement. The software will automatically export the pressure data.

For structure parameter measurement of the compressed hosiery samples, place a directly measured sample onto the artificial lower limb and use a tape measure to measure the total length of the sample. Use a pick glass to measure the course density and the wales density of each divided part and use the measuring tape to measure the circumference of each circle line. When all of the structure parameter measurements have been acquired, remove the sample from the limb and measure the circumference of each circle line and the course and wales densities of the undressed sample.

To acquire a thickness measurement, smooth a compressed hosiery sample onto the steel round table of the thickness gauge and turn on the gauge. Let another steel round slowly fall down to press onto the sample piece. The screen will display the thickness data.

To perform a tensile experiment, first cut the compressed hosiery sample along the marked circle lines and clamp one piece of sample into the tensile testing instrument. Next, open the software of the tensile instrument and enter five Newtons as the initial tension, 60 millimeters per minute as the tensile speed, and 200 millimeters as the initial tensile strength. When all of the measurement parameters have been set, click Start.

The computer will export the real-time stress and strain on the screen, and the tensile experiment will automatically stop when the compressed hosiery piece is broken. Then, replace the broken piece of sample with a new sample piece for the next round of testing. The course density of the fabricated compressed hosiery sample gradually increases from the knee to the ankle.

In the fabrication process, the graduation affects the sinking depth of the needle. Thus, the compressed hosiery samples fabricated with the highest graduation value demonstrate the lowest wales densities and vice versa. The use of an elastic motor has a significant effect on the circumference and cross density of the divided parts, while graduation exerts a significant effect on the wales density.

Here, representative pressure data obtained from direct and indirect measurements can be observed. From the ankle to the knee, the exerted pressure magnitude of all of the compressed hosiery samples gradually declined, and it is clear that the cylinder model measurements slightly deviated from the direct measurements, indicating that the predicted pressure data from the cylinder model was inconsistent with the measured pressure. To further quantitatively study the differences between the cone and cylinder models, the Spearman correlation method can be used.

For example, in this analysis, the correlation coefficient between the cone model and the measured pressure was higher than the correlation between the cylinder model and the measured pressure, indicating that the cone model is a better model for predicting the pressure characteristic than the cylinder model. The samples should be knitted or woven and acquired not commercially. The pressure can be measured on human skin.

The result will differ from those measured for artificial legs, as the former provides a softer surface than the latter. The cone model more accurately than the cylinder model. Therefore, future compression garment pressure measurements should be performed directly on the cone model.