TWO-DIMENSIONAL FINITE ELEMENT MODEL TO STUDY THERMO BIOMECHANICS IN PERIPHERAL REGIONS OF HUMAN LIMBS DUE TO EXERCISE IN COLD CLIMATE

2017 ◽  
Vol 17 (01) ◽  
pp. 1750002 ◽  
Author(s):  
BABITA KUMARI ◽  
NEERU ADLAKHA
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Physical Exercise ◽  
Peripheral Region ◽  
Cold Climate ◽  
Two Dimensional ◽  
Human Beings ◽  
Thermal Dynamics ◽  
Thermal Injuries ◽  
The Impact

Human beings are equipped with thermo sensitivity, thermoregulation and thermo protection for maintaining the structure and function of their body organs. The thermoregulatory responses and disturbances caused by physical activity in thermo biomechanics of human body organs are not well understood. The mechanism of thermoregulation exhibits a beautiful coordination of biophysical process in order to balance distribution caused by a biothermal system due to physical exercise and other abnormal conditions. In view of above, a model has been developed to study the thermal dynamics in peripheral region of human limbs immediately after exercise under cold climatic conditions. The human limb is assumed to be of cylindrical shape. The peripheral region of limb is divided into three natural components namely epidermis, dermis and subdermal tissues. Appropriate boundary conditions have been framed based on the physical condition of the problem. Finite difference has been employed for time variable and the finite element method is employed along radial and angular direction. The numerical results have been used to obtain temperature profiles in the peripheral region immediately after continuous exercise for a two-dimensional unsteady state case. These results have been used to analyze the thermal disturbances caused by the different intensities of physical exercise in the peripheral region of human limbs. Such a model can be developed to study the generated thermal information which can be useful to biomedical science to analyze the impact of thermal stress on mechanism of thermoregulation causing thermal injuries like heat cramps, heat exhaustion and heat stroke. The results give the idea about the capacity of biothermo mechanisms of human limbs in counting balance. The thermal stress is caused by different intensities of physical exercise. These results can be useful for the biomedical scientists to understand the thermal discomfort caused by different intensities of physical exercise and the time period of rest required to overcome discomfort. Further, the result can be useful to biomedical scientists for developing protocols for physical exercise and rest required by the subject for different intensities of physical exercise and prevent thermal injuries in the workers and sportsmen.

Two-dimensional finite difference model to study temperature distribution in SST regions of human limbs immediately after physical exercise in cold climate

2015 ◽  
Vol 04 (01) ◽  
pp. 1550002
Author(s):  
Babita Kumari ◽  
Neeru Adlakha
Keyword(s):  
Thermal Stress ◽  
Heat Exchange ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Physical Exercise ◽  
Peripheral Region ◽  
Cold Climate ◽  
The Body ◽  
Cylindrical Shape ◽  
Two Dimensional

Thermoregulation is a complex mechanism regulating heat production within the body (chemical thermoregulation) and heat exchange between the body and the environment (physical thermoregulation) in such a way that the heat exchange is balanced and deep body temperatures are relatively stable. The external heat transfer mechanisms are radiation, conduction, convection and evaporation. The physical activity causes thermal stress and poses challenges for this thermoregulation. In this paper, a model has been developed to study temperature distribution in SST regions of human limbs immediately after physical exercise under cold climate. It is assumed that the subject is doing exercise initially and comes to rest at time t = 0. The human limb is assumed to be of cylindrical shape. The peripheral region of limb is divided into three natural components namely epidermis, dermis and subdermal tissues (SST). Appropriate boundary conditions have been framed based on the physical conditions of the problem. Finite difference has been employed for time, radial and angular variables. The numerical results have been used to obtain temperature profiles in the SST region immediately after continuous exercise for a two-dimensional unsteady state case. The results have been used to analyze the thermal stress in relation to light, moderate and vigorous intensity exercise.

Numerical Simulation of Fracture Process of Concrete Dam due to Freezing and Thawing with Finite Element Method

2007 ◽  
Vol 348-349 ◽  
pp. 941-944
Author(s):  
Li Juan Cao ◽  
Shou Ju Li ◽  
Zi Chang Shangguan
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Cold Climate ◽  
Temperature Fields ◽  
Stress Fields ◽  
Freezing And Thawing ◽  
Concrete Dam ◽  
Element Method

Freezing and thawing damage is one of the major problems of concrete dams in cold climate. Cracking and splitting are the most common results of freezing and thawing deterioration in concrete dam. The cracking problem owing to freezing and thawing was investigated by making sue of finite element methods. The interpretation of the mechanism of failure was also given. In order to compute the thermal stress fields of concrete dam caused by freezing and thawing, the temperature changes versus seasons is determined according to measured data. The temperature fields of concrete dam versus seasons are simulated by using finite element method. Basing on the computational results of the temperature fields of concrete dam, the thermal stress fields are calculated numerically. The researches show that the first principal stress of concrete dam at downstream surface can exceed the tensile strength of concrete material. The numerical simulation results of fractured regions of concrete dam agreed with practical observed data.

DNB Oscillatory Temperature and Thermal Stress Responses for Evaporator Tubes Based on Rivulet Model

1978 ◽  
Vol 100 (3) ◽  
pp. 424-431 ◽  
Author(s):  
C. L. Chu ◽  
J. M. Roberts ◽  
A. W. Dalcher
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Temperature Variation ◽  
Stress Responses ◽  
Thermal Model ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Computer Codes ◽  
Oscillatory Temperature

Experiment evidence and observations have shown that the DNB oscillation phenomena can best be characterized by water rivulets motion with temperature variation in the circumferential direction. This paper presents the rivulet thermal model that directly corresponds to these observations. Finite element computer codes were used to evaluate temperature and thermal stress behavior of the steam tube under the condition where water rivulets appear and disappear along the tube inside circumference. An inherently complicated three-dimensional problem can reasonably be reduced to a two-dimensional analysis with relative simplicity.

Cohesive Finite Element Simulation of the Impact Response of Polymer Bonded Explosives

2009 ◽  
Author(s):  
A. Barua ◽  
M. Zhou
Keyword(s):  
Finite Element ◽  
Impact Response ◽  
Two Dimensional ◽  
Cohesive Elements ◽  
Failure Characteristics ◽  
Contact Algorithm ◽  
Element Simulation ◽  
Polymer Bonded Explosives ◽  
The Impact ◽  
Crack Paths

The impact response of HMX/Estane, a Polymer Bonded Explosive (PBX), is analyzed under two-dimensional plane-strain conditions using a cohesive finite element method (CFEM). The framework enables the consideration of arbitrary microstructures. The binder polymer is modeled as a viscoelastic material. The dependence of elastic modulus on temperature across the glass transition temperature Tg (= 233 K) is considered in the constitutive framework. Also, the HMX crystals are assumed to be elastic under the conditions analyzed. Cohesive elements are implemented throughout the microstructure, allowing explicit tracking of arbitrary crack paths through each constituent or interfaces between the constituents. A contact algorithm used to track and account for the interactions between failed crack surfaces. The simulations capture the failure characteristics observed experimentally at temperatures ranging from below to above Tg of the polymer.

Thermal Stress in Discretely Layered Structures with Functional Graded Materials

2008 ◽  
Vol 24 (4) ◽  
pp. 297-300 ◽  
Author(s):  
S.-F. Hwang ◽  
W.-T. Liao
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Layered Structures ◽  
Two Dimensional ◽  
Element Analysis ◽  
Graded Materials ◽  
Dimensional Finite Element ◽  
Graded Material

AbstractFunctional graded materials are generally provided in discretely layered structures to reduce the abrupt mismatch and to improve failure performance. To investigate the thermal stress singularity occurring at the intersection of an interface and a free end, two-dimensional and three-dimensional finite element analyses are performed for titanium and aluminum layers with or without functional graded materials. The results indicate that once the functional graded material is added, the stress singularity around the intersection of an interface and a free end could be significantly relieved. If more FGM layers are used, the stress singularity could be further reduced to a very small value. If the longitudinal normal stresses and interlaminar shear stress are considered, two-dimensional finite element analysis may be enough, while three-dimensional analysis is necessary for the interlaminar normal stress. Otherwise, one may underestimate its stress singularity.

Role of Material Properties in the Finite Element Solution for Three-Dimensional Composites—A Sensitivity Study

1995 ◽  
Vol 209 (2) ◽  
pp. 157-160
Author(s):  
H-B Hellweg ◽  
M A Crisfield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Transversely Isotropic ◽  
Sensitivity Study ◽  
Two Dimensional ◽  
Element Analysis ◽  
The Impact

Three-dimensional material test data for orthotropic laminae are difficult to obtain. Consequently, various simplifications are made for the material properties of individual layers in a finite element analysis, ranging from the assumption of transversely isotropic layers to applying two-dimensional material data in a three-dimensional analysis. In order to investigate the impact and validity of such simplifications, the sensitivity of the stresses and deformations in a finite element analysis on the material properties was investigated.

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