Ameersing Luximon

Foot Shape Modeling

This study is an attempt to show how a “standard” foot can be parameterized using foot length, foot width, foot height, and a measure of foot curvature so that foot shape can be predicted using these simple anthropometric measures. The prediction model was generated using 40 Hong Kong Chinese men, and the model was validated using a different group of 25 Hong Kong Chinese men. The results show that each individual foot shape may be predicted to a mean accuracy of 2.1 mm for the left foot and 2.4 mm for the right foot. Application of this research includes the potential design and development of custom footwear without the necessity of expensive 3-D scanning of feet.

3D foot shape generation from 2D information

Two methods to generate an individual 3D foot shape from 2D information are proposed. A standard foot shape was first generated and then scaled based on known 2D information. In the first method, the foot outline and the foot height were used, and in the second, the foot outline and the foot profile were used. The models were developed using 40 participants and then validated using a different set of 40 participants. Results show that each individual foot shape can be predicted within a mean absolute error of 1.36 mm for the left foot and 1.37 mm for the right foot using the first method, and within a mean absolute error of 1.02 mm for the left foot and 1.02 mm for the right foot using the second method. The second method shows somewhat improved accuracy even though it requires two images. Both the methods are relatively cheaper than using a scanner to determine the 3D foot shape for custom footwear design.

Shoe-last design innovation for better shoe fitting

Shoe-last, a 3D mould used for making footwear, influence the shape, size and fitting of footwear. Current shoe-last design software has focused mainly on reverse engineering of existing shoe-last and modification. Shoe-last designers have generally preferred to design the shoe-last manually due to limitations of design software. In order to solve these problems, a new software based on CATIA platform was developed. The shoe-last model is based on foot shape measurement data and foot biomechanics. Using the existing shoe-last design standards and the sections from existing shoe-lasts, design tables and relationship equations enables the design of shoe-last with different toe type, heel height and custom shoe-last. The design includes comfort and fit aspects as well as design aspect, therefore enables design of aesthetical comfortable shoes. Since the design can be modified instantaneously, the designers could visualize design changes leading to a reduction in shoe-last design cycle.

The Quality of Footwear Fit: What we know, don't know and should know

Even though fit ranks as one of the most important considerations in the purchase of a shoe, the quality of fit has no metric and is hence poorly assessed. Manufacturers, retailers, and customers tend to use trial and error techniques to improve footwear fit. This approach is rather cumbersome and very unscientific. In this paper, we present a methodology to assess and thereby quantify footwear fit so that comfort can be predicted and consequently improved lasts and shoes can be produced that match different shapes of feet.

Foot Flare and Foot Axis

Most commercial footwear is designed and manufactured on a curved last, although the amount of curvature of the last and the turning point of the last centerline have not been formally determined. In this study, we used principal component analysis to determine the foot axis so that lasts that match feet can be produced, resulting in a good fit. In evaluating 50 Hong Kong Chinese participants, we found that the center of the foot is located at approximately 52% of the foot length measuring from the back of the foot (SD = 0.65%) and that Hong Kong participants have a mean inflare (inward curvature) of 3.2°. The foot center and inflare measures will help determine the fit between footwear and feet. Applications of this research include the ability to incorporate foot flare into the design and manufacture of footwear.

Sizing and grading for wearable products

Sizing and grading are widely used to create products to fit selected populations. Currently, the sizing and grading rules are derived from anthropometric measures; however past researches have indicated that it is not very accurate. This study proposes a new technique to use principal component analysis (PCA) on 3D surface points for sizing and grading wearable products. The accuracy of the proposed method is illustrated by developing a sizing and grading rule for the feet. After developing a model using the feet data of 60 participants and validating using the feet data of 10 different participants, results showed that sizing and grading using PCA is more accurate than traditional techniques. Compared with traditional foot sizing, PCA based sizing and grading showed an improvement of about 25% in accuracy. In addition, results also indicated that the grading rule derived from PCA loading was better than the proportional grading. This research provides a new direction to consider when developing the sizing and grading rules. It can be extended to calculate the number of sizes and the size increment for various wearable products.

Finite element modeling of male leg and sportswear: contact pressure and clothing deformation

In clinical practice, fast assessment of contact pressure is usually calculated by Laplace’s Law, which neither provides detailed surface geometry for soft materials of the leg, nor offers sufficient predictive power for designing high-performance sportswear. To bridge this gap, this paper describes a finite element (FE) model of sports tights that was developed with a detailed anatomic male leg model to predict the compression effects of high-performance sportswear. Non-linear elastic material was applied on the sportswear material to model the large deformation behavior. Experimental validation on athletes was performed. A reasonable agreement was found in the experimental validation. Suitable profiles were achieved along the height of the leg, in terms of both contact pressure and clothing deformation (true strain or logarithmic strain). The maximum contact pressure (2222 Pa) occurred on the posterior of the ankle, while the maximum principal true strain of the sports tights occurred on the edge of the upper thigh. This study indicates that the proposed FE model is useful for the assessment of contact pressure distribution in sportswear.

Prediction of drape profile of cotton woven fabrics using artificial neural network and multiple regression method

Fabric drape is one of the most important factors which affect the graceful appearance of the garment. The drape coefficient is the widely used parameter to describe fabric drape but it needs other parameters to explain the fabric behavior. In this study, we have investigated the relationship between the fabric drape parameters such as drape coefficient, drape distance ratio, fold depth index, amplitude and number of nodes and low stress mechanical properties. Drape parameters were tested on a specially developed instrument based on a digital image processing technique and the low stress mechanical properties were tested by the Kawabata evaluation system. Then the drape parameters were predicted by constructing models using multiple regressions method and feed-forward back-propagation neural network technique. Simple equations are derived using regressions method to predict the five shape parameters of drape profile from the low stress mechanical properties. It is observed that bending, shear and aerial density affect the drape parameters most whereas the tensile and compression have little effect on the drape parameters.

Effects of heel base size, walking speed, and slope angle on center of pressure trajectory and plantar pressure when wearing high-heeled shoes

High-heeled shoes are associated with instability and a high risk of fall, fracture, and ankle sprain. This study investigated the effects of heel base size (HBS) on walking stability under different walking speeds and slope angles. The trajectory of the center of pressure (COP), maximal peak pressure, pressure time integral, contact area, and perceived stability were analyzed. The results revealed that a small HBS increased the COP deviations, shifting the COP more medially at the beginning of the gait cycle. The slope angle mainly affected the COP in the anteroposterior direction. An increased slope angle shifted the COP posterior and caused greater pressure and a larger contact area in the midfoot and rearfoot regions, which can provide more support. Subjective measures on perceived stability were consistent with objective measures. The results suggested that high-heeled shoes with a small HBS did not provide stable plantar support, particularly on a small slope angle. The changes in the COP and pressure pattern caused by a small HBS might increase joint torque and muscle activity and induce lower limb problems.

Nano-Mg–Al-layered double hydroxide application to cotton for enhancing mechanical, UV protection and flame retardancy at low cytotoxicity level

The synthesis and application of layered double hydroxide (LDH) is gaining impetus for developing nano-hybrids with desired functionality. They are environmentally benign and of potential use in biotechnology, pharmaceuticals, drug design, flame retardancy, separation and membrane technology, filtration, scavenging and controlled release of anions, electro-active and photoactive materials. However, there has been a limited research in wearable textile applications. In this study, magnesium–aluminium LDH nano-particles were synthesized and applied to cotton fabric to enhance mechanical, ultraviolet protection and flame retardancy properties. In addition, their cytotoxicity tests were investigated to ensure safe wearable applications. It was found that the application of this Mg–Al nano-LDH (1.5%) with reactive remazol dye (98.5%) at 2% shade improved the UV protection (UV protection factor: 20.184), enhanced flame-suppressing capacity (limiting oxygen index from 16.5 to 20.8) with significantly increased tensile strength (76.85%) of cotton.