This paper proposed an innovative teaching approach based on finite element technique(FET)to improve the understanding of material mechanics.A teaching experiment was conducted using pure bending deformation of a beam...This paper proposed an innovative teaching approach based on finite element technique(FET)to improve the understanding of material mechanics.A teaching experiment was conducted using pure bending deformation of a beam as an example,and the deformation and stress distribution of the beam were analyzed using FET.The results showed that using color stress nephograms and color U nephograms can improve students’learning outcomes in mechanics classroom.The high levels of satisfaction and interest in incorporating new techniques into the classroom suggest that there is a need to explore and develop innovative teaching methods in mechanics and related fields.This approach may inspire educators to develop more effective ways of teaching material mechanics,and our research can contribute to the advancement of mechanics education.展开更多
Nonlinear solution of reinforced concrete structures, particularly complete load-deflection response, requires tracing of the equilibrium path and proper treatment of the limit and bifurcation points. In this regard, ...Nonlinear solution of reinforced concrete structures, particularly complete load-deflection response, requires tracing of the equilibrium path and proper treatment of the limit and bifurcation points. In this regard, ordinary solution techniques lead to instability near the limit points and also have problems in case of snap-through and snap-back. Thus they fail to predict the complete load-displacement response. The arc-length method serves the purpose well in principle, received wide acceptance in finite element analysis, and has been used extensively. However modifications to the basic idea are vital to meet the particular needs of the analysis. This paper reviews some of the recent developments of the method in the last two decades, with particular emphasis on nonlinear finite element analysis of reinforced concrete structures.展开更多
During wound healing, the metabolic activity associated with each phase must occur in the proper sequence, at a specific time, and continue for a specific duration at an optimal intensity. Any disturbance in appropria...During wound healing, the metabolic activity associated with each phase must occur in the proper sequence, at a specific time, and continue for a specific duration at an optimal intensity. Any disturbance in appropriate thermal environment may complicate the wound healing process and may give rise to wound infection. In the presented paper a transient state two-dimensional mathematical model has been developed to analyse thermal variations in skin and subcutaneous tissue (SST) region of human limb. Due to circular shape of human limb, model has been developed in polar coordinates. The domain of the study consists of two types of tissues: abnormal tissues and normal tissues. The post surgery peripheral tissue of human limb during healing time is considered as abnormal tissues. The effect of variable density of blood vessels in dermal layer of both tissues on the physical and physiological parameters is incorporated in the model. The effect of healing on physiological parameters of abnormal tissue is incorporated by considering the physiological parameters to be function of time “t”. The effect of different climatic conditions is considered in the model. Taking into account the variable core temperature due to anatomy of arteries and variable physiological parameters in dermal layer of peripheral region, the well known Pennes’ bio heat equation is used to analyse the time-dependent temperature distribution of both normal and abnormal tissues. Comparison between temperature profiles of both normal and abnormal tissue has been done using finite element approach with bilinear shape functions in polar coordinates. A computer program in MATLAB has been developed to simulate the results.展开更多
The rapid movement of heat transferred goes to be the most important target for researchers to deals with the thermal problems of electronic systems.Especially,that has high packing densities in limited space.Conseque...The rapid movement of heat transferred goes to be the most important target for researchers to deals with the thermal problems of electronic systems.Especially,that has high packing densities in limited space.Consequently,vertical combination between two shapes of fins was considered to improve the thermal performance of heat sink.Here,many models(longitudinal-pin fins)were created as a new approach based on the stable both of material and size.In the analytical solution,Finite element techniques used to solve the mathematical modeling and signum-sinusoidal-signum function was modified to model both the variable heat transfer area and convection perimeter.While in the numerical procedure,ANSYS simulation used as the validation of temperature distribution.In addition,results from previous work were used as second method of validation process.The results show a high level of agreement by maximum difference does not exceed(3.52%).In the calculation process,natural convection,range of Ra number(105–107)were applied for all models of which each one is distinguished by the parameter of area ratio(A∗)between hybrid model and longitudinal model.The results show many advantages;a significant drop in temperature profile about(2.7%–8.8%).Also,decrease in thermal resistance by(23%–43%)and increases in heat transferred(29%–78%).Furthermore,all parameters have a significant improve for the models that have A∗<1.48.But this improvement was down to less level at A∗>1.48 as a result of overlapping between the effects of miscellaneous parameters.Irreversibility that associated with the entropy generation was considered.In this step,it becomes important to find the model that achieves maximize of the thermal performance and minimize of the entropy generation.For that,the optimization procedure using genetic algorithm was adopted.It's clearly the best model exist within a close range between 1.509 and 1.518 based on the behavior of the best fitness function.展开更多
文摘This paper proposed an innovative teaching approach based on finite element technique(FET)to improve the understanding of material mechanics.A teaching experiment was conducted using pure bending deformation of a beam as an example,and the deformation and stress distribution of the beam were analyzed using FET.The results showed that using color stress nephograms and color U nephograms can improve students’learning outcomes in mechanics classroom.The high levels of satisfaction and interest in incorporating new techniques into the classroom suggest that there is a need to explore and develop innovative teaching methods in mechanics and related fields.This approach may inspire educators to develop more effective ways of teaching material mechanics,and our research can contribute to the advancement of mechanics education.
文摘Nonlinear solution of reinforced concrete structures, particularly complete load-deflection response, requires tracing of the equilibrium path and proper treatment of the limit and bifurcation points. In this regard, ordinary solution techniques lead to instability near the limit points and also have problems in case of snap-through and snap-back. Thus they fail to predict the complete load-displacement response. The arc-length method serves the purpose well in principle, received wide acceptance in finite element analysis, and has been used extensively. However modifications to the basic idea are vital to meet the particular needs of the analysis. This paper reviews some of the recent developments of the method in the last two decades, with particular emphasis on nonlinear finite element analysis of reinforced concrete structures.
文摘During wound healing, the metabolic activity associated with each phase must occur in the proper sequence, at a specific time, and continue for a specific duration at an optimal intensity. Any disturbance in appropriate thermal environment may complicate the wound healing process and may give rise to wound infection. In the presented paper a transient state two-dimensional mathematical model has been developed to analyse thermal variations in skin and subcutaneous tissue (SST) region of human limb. Due to circular shape of human limb, model has been developed in polar coordinates. The domain of the study consists of two types of tissues: abnormal tissues and normal tissues. The post surgery peripheral tissue of human limb during healing time is considered as abnormal tissues. The effect of variable density of blood vessels in dermal layer of both tissues on the physical and physiological parameters is incorporated in the model. The effect of healing on physiological parameters of abnormal tissue is incorporated by considering the physiological parameters to be function of time “t”. The effect of different climatic conditions is considered in the model. Taking into account the variable core temperature due to anatomy of arteries and variable physiological parameters in dermal layer of peripheral region, the well known Pennes’ bio heat equation is used to analyse the time-dependent temperature distribution of both normal and abnormal tissues. Comparison between temperature profiles of both normal and abnormal tissue has been done using finite element approach with bilinear shape functions in polar coordinates. A computer program in MATLAB has been developed to simulate the results.
文摘The rapid movement of heat transferred goes to be the most important target for researchers to deals with the thermal problems of electronic systems.Especially,that has high packing densities in limited space.Consequently,vertical combination between two shapes of fins was considered to improve the thermal performance of heat sink.Here,many models(longitudinal-pin fins)were created as a new approach based on the stable both of material and size.In the analytical solution,Finite element techniques used to solve the mathematical modeling and signum-sinusoidal-signum function was modified to model both the variable heat transfer area and convection perimeter.While in the numerical procedure,ANSYS simulation used as the validation of temperature distribution.In addition,results from previous work were used as second method of validation process.The results show a high level of agreement by maximum difference does not exceed(3.52%).In the calculation process,natural convection,range of Ra number(105–107)were applied for all models of which each one is distinguished by the parameter of area ratio(A∗)between hybrid model and longitudinal model.The results show many advantages;a significant drop in temperature profile about(2.7%–8.8%).Also,decrease in thermal resistance by(23%–43%)and increases in heat transferred(29%–78%).Furthermore,all parameters have a significant improve for the models that have A∗<1.48.But this improvement was down to less level at A∗>1.48 as a result of overlapping between the effects of miscellaneous parameters.Irreversibility that associated with the entropy generation was considered.In this step,it becomes important to find the model that achieves maximize of the thermal performance and minimize of the entropy generation.For that,the optimization procedure using genetic algorithm was adopted.It's clearly the best model exist within a close range between 1.509 and 1.518 based on the behavior of the best fitness function.
