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Heng Wang - One of the best experts on this subject based on the ideXlab platform.

  • Loading pattern of postoperative hallux valgus feet with and without transfer metatarsalgia a case control study
    Journal of Orthopaedic Surgery and Research, 2017
    Co-Authors: Xiang Geng, Dichao Huang, Xu Wang, Chao Zhang, Jiazhang Huang, Li Chen, Chen Wang, Junsheng Yang, Heng Wang
    Abstract:

    Postoperative transfer metatarsalgia is a common complication after hallux valgus surgeries. Shortening of the first metatarsal is traditionally thought to be the primary cause of it. However, we speculate the abnormal Loading pattern during gait is the real reason. This study is to determine specific differences in the Loading patterns between reconstructive hallux valgus (HV) feet with and without postoperative transfer metatarsalgia, so as to find risky Loading characteristics of this complication. Thirty feet with postoperative transfer metatarsalgia were recruited as pain group, while another 30 postoperative feet without pain as controls. All participants were asked to walk barefoot at self-selected speed through a plantar force measuring plate (Rs-Scan Inc.) for three times. Certain plantar Load variables were recorded or calculated, and their differences between two groups were compared. For pain group, the maximum plantar force and force time integral of the first metatarsal decrease significantly; the force time integral of the central rays (second plus third metatarsal) does not significantly differ with that in the controls, but their cumulative Load percentage to the whole foot is higher. In pain group, the time point when central rays reached their peak force during the push-off is significantly later than that in controls. And the regional instant Load percentage at this moment presented significantly higher for central rays, while significantly lower for the first metatarsal and the hallux compared to the controls. For hallux valgus feet with postoperative metatarsalgia, the Load Function of the first metatarsal is obviously impaired. But for central rays, indicative difference is not reflected in either peak or cumulative Load during the gait cycle, but in the instant Load distribution when central rays reach their peak Load. So we can conclude that whether the remaining regions can adequately share certain Load during walking, especially around the time metatarsalgia often occurs, plays an unnegligible role. So surgeons should pay more attention to reconstruct a foot where Load can be evenly distributed.

  • Loading pattern of postoperative hallux valgus feet with and without transfer metatarsalgia: a case control study
    BMC, 2017
    Co-Authors: Xiang Geng, Dichao Huang, Xu Wang, Chao Zhang, Jiazhang Huang, Li Chen, Chen Wang, Junsheng Yang, Heng Wang
    Abstract:

    Abstract Background Postoperative transfer metatarsalgia is a common complication after hallux valgus surgeries. Shortening of the first metatarsal is traditionally thought to be the primary cause of it. However, we speculate the abnormal Loading pattern during gait is the real reason. This study is to determine specific differences in the Loading patterns between reconstructive hallux valgus (HV) feet with and without postoperative transfer metatarsalgia, so as to find risky Loading characteristics of this complication. Methods Thirty feet with postoperative transfer metatarsalgia were recruited as pain group, while another 30 postoperative feet without pain as controls. All participants were asked to walk barefoot at self-selected speed through a plantar force measuring plate (Rs-Scan Inc.) for three times. Certain plantar Load variables were recorded or calculated, and their differences between two groups were compared. Results For pain group, the maximum plantar force and force time integral of the first metatarsal decrease significantly; the force time integral of the central rays (second plus third metatarsal) does not significantly differ with that in the controls, but their cumulative Load percentage to the whole foot is higher. In pain group, the time point when central rays reached their peak force during the push-off is significantly later than that in controls. And the regional instant Load percentage at this moment presented significantly higher for central rays, while significantly lower for the first metatarsal and the hallux compared to the controls. Conclusions For hallux valgus feet with postoperative metatarsalgia, the Load Function of the first metatarsal is obviously impaired. But for central rays, indicative difference is not reflected in either peak or cumulative Load during the gait cycle, but in the instant Load distribution when central rays reach their peak Load. So we can conclude that whether the remaining regions can adequately share certain Load during walking, especially around the time metatarsalgia often occurs, plays an unnegligible role. So surgeons should pay more attention to reconstruct a foot where Load can be evenly distributed

Luke A. Louca - One of the best experts on this subject based on the ideXlab platform.

A S Fallah - One of the best experts on this subject based on the ideXlab platform.

  • dynamic performance of simply supported rigid plastic square plates subject to localized blast Loading
    Journal of Engineering Mechanics-asce, 2019
    Co-Authors: N Mehregania, A S Fallah, Luke A. Louca
    Abstract:

    AbstractThis paper presents the theoretical solution to the response of a square plate undergoing plastic deformation due to a generic localized blast pulse. A localized blast Load Function was ass...

  • Dynamic Performance of Simply Supported Rigid-Plastic Square Plates Subject to Localized Blast Loading
    'American Society of Civil Engineers (ASCE)', 2018
    Co-Authors: Mehreganian N, A S Fallah, La Louca
    Abstract:

    This paper presents the theoretical solution to the response of a square plate undergoing plastic deformation due to a generic localized blast pulse. A localized blast Load Function was assumed multiplicative of its spatial distribution and temporal pulse shape. The spatial distribution was representative of constant pressure over the central zone, while exponentially decaying outside that zone. Considering an appropriate moment Function and ignoring the membrane, transverse shear, and rotary inertia effects, the static plastic collapse was found, whereby the analysis was extended to the dynamic case by assuming a kinematically admissible, time-dependent velocity profile. The analytical model, which was validated against the numerical results obtained through ABAQUS hydrocode, showed close correlation in terms of the permanent transverse deflection profile. In order to consider the effect of temporal pulse shape, the results were formulated for rectangular as well as exponentially and linearly decaying pulses. For blast Loads of high magnitude, the pressure Load was replaced by an impulsive velocity. The calculations were simplified by utilizing the dimensionless form, and the results were corroborated with theoretical and experimental results from the literature. The model showed improvements in predicting the final deformation of square plates over previous models of simplified Loading Function

La Louca - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Performance of Simply Supported Rigid-Plastic Square Plates Subject to Localized Blast Loading
    'American Society of Civil Engineers (ASCE)', 2018
    Co-Authors: Mehreganian N, A S Fallah, La Louca
    Abstract:

    This paper presents the theoretical solution to the response of a square plate undergoing plastic deformation due to a generic localized blast pulse. A localized blast Load Function was assumed multiplicative of its spatial distribution and temporal pulse shape. The spatial distribution was representative of constant pressure over the central zone, while exponentially decaying outside that zone. Considering an appropriate moment Function and ignoring the membrane, transverse shear, and rotary inertia effects, the static plastic collapse was found, whereby the analysis was extended to the dynamic case by assuming a kinematically admissible, time-dependent velocity profile. The analytical model, which was validated against the numerical results obtained through ABAQUS hydrocode, showed close correlation in terms of the permanent transverse deflection profile. In order to consider the effect of temporal pulse shape, the results were formulated for rectangular as well as exponentially and linearly decaying pulses. For blast Loads of high magnitude, the pressure Load was replaced by an impulsive velocity. The calculations were simplified by utilizing the dimensionless form, and the results were corroborated with theoretical and experimental results from the literature. The model showed improvements in predicting the final deformation of square plates over previous models of simplified Loading Function

Raymond M. Kolonay - One of the best experts on this subject based on the ideXlab platform.

  • Load paths visualization in plane elasticity using Load Function method
    International Journal of Solids and Structures, 2018
    Co-Authors: Ali Yeilaghi Tamijani, Kaveh Gharibi, Marcelo H. Kobayashi, Raymond M. Kolonay
    Abstract:

    Abstract The paper proposes a Load Function method for Load path visualization and Load flow calculation in plane elasticity problems. The Load Functions are directly derived from 2D equilibrium equations. The stresses are written in terms of the Load Functions and the Load flow is calculated using the Load Function gradient. The Load Functions are defined using generalized Beltrami representation. A constructive proof is given for the existence of Load Functions. A set of Poisson's equations in terms of Load Functions and stress components are developed and an efficient numerical procedure to solve them is discussed. Numerical results show the proposed Load Function method is able to define the Load paths and obtain the Load flow using an Airy stress Function for problems with available closed form solution, and also can be easily integrated into the numerical approaches to calculate Load paths for complex problems.