Aquatic and terrestrial animals have different swimming performances and mechanical efficiencies based on their different swimming methods. To explore propulsion in swimming frogs, this study ...calculated mechanical efficiencies based on data describing aquatic and terrestrial webbed-foot shapes and swimming patterns. First, a simplified frog model and dynamic equation were established, and hydrodynamic forces on the foot were computed according to computational fluid dynamic calculations. Then, a two-link mechanism was used to stand in for the diverse and complicated hind legs found in different frog species, in order to simplify the input work calculation. Joint torques were derived based on the virtual work principle to compute the efficiency of foot propulsion. Finally, two feet and swimming patterns were combined to compute propulsive efficiency. The aquatic frog demonstrated a propulsive efficiency (43.11%) between those of drag-based and lift-based propulsions, while the terrestrial frog efficiency (29.58%) fell within the range of drag-based propulsion. The results illustrate the main factor of swimming patterns for swimming performance and efficiency.
This study introduces a turning function based technique to classify foot outlines. Foot scans from ten males and ten females were obtained using a laser scanner. The similarities among the different ...foot shapes were assessed based on the Euclidean distance between turning functions. Thereafter, average linkage clustering was used to classify the differing foot outlines. Two distinct shape groups emerged for both medial and lateral sides. The presence or absence of a medial bulge results in two clusters on the medial side. Similarly, a narrow lateral side with more concavity and a wider lateral side in the midfoot region are the two clusters for the lateral side. More males (60%) showed a bulge on the medial side. The group that belongs to the narrower lateral side were predominantly females (70%). These differences in the structure of the clusters were reflected in the lack of a correlation between the medial and lateral side clusters.
In order to analyze the influence of rigid foot's geometry shape of legged robot on the sinking process in soft soil, MAT 147 material is used as the constitutive model of soil and the dynamic ...simulation of rigid foot's sinking process is carried out with Multi Material Arbitrary Lagrangian Eulerian(MM-ALE) method. The plate sinking test is simulated with MM-ALE method and the results are compared with the results from empirical formula proposed by Bekker. The results show that the maximum effective stress of soil concentrates at the bottom of the rigid foot near the edge and increases with the sinking of rigid foot, while the overall stress distributions are similar. The sinking depth has great influence on the range of the disturbed soil. The relationship between rigid foot's fillet radius and the stress distribution in the horizontal and vertical direction are studied and the soft soil flow trend are also analyzed. The results indicate that the bigger the fillet radius is, the more uniform the soil stress distribution at the bottom, but it has little influence on the side. Another finding is that the sinking depth has a positive correlation with fillet radius under the same pressure, while the maximum effective stress is opposite.
The health of feet is connected with individual's health and affects a man's activity. Shoes need to be designed to protect feet and to absorb the impact of land. In order to choose suitable shoes ...for feet, the foot size and shape must be considered, so it is essential to grasp the exact size and shape of the foot. This study aims to present fundamental data on shoes' easy order prototype development for choosing shoes of good wearing comfort, by classifying feet size and shape junior high school boys in the early adolescent period. The subject were 217 Korean junior high school girls in age from 14 to 16 years old. The subjects were directly measured anthropometrically and indirectly analyzed photographically. 7 factors were extracted through factor analysis and those factors comprised 78.59% of total variance. The factors were characterized foot length, foot girth and width, foot shape around the fifth toes, foot shape around the first toes, angle of foot breadth, foot height, and foot length of upper foot. 3 clusters as their foot shape were categorized using 7 factor scores by cluster analysis. Type 1 had smaller in foot girth, width and length than other types and with deformed fifth toe. Type 2 had average size and high foot shape. Type 3 was characterized by long large foot with deformed first toe. The results would be a great support in producing and choosing appropriate shoes if forms are classified by subdividing foot form classification and extract a factor which shows only the foot sole shape.
In this paper, we use instruments to scan the feet of athletes with no foot disease or previous injury from Beijing Sport University and ordinary college students from Tsinghua University and obtain ...the foot shapes and the changes therein of the subjects. Then we design and extract indices like foot length and foot width, perform statistic analysis of the foot shapes of young athletes under different loads, and obtain a group of data regarding the foot shape features of young athletes under different loads. This group of data can provide experimental operation experience and data support for the establishment of national young athlete foot shape index database. By analyzing the differences between the foot shape indices of young athletes under different loads, we find that different loads have some impacts on the foot shape changes. There are great differences between the foot shape indices of young athletes and ordinary college students in China, and of the young athletes in China, foot shape indices like foot length and width are likely to vary greatly due to different loads.
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