18 research outputs found
INTRINSIC VARIABLES OF CONSTITUTIVE EQUATION
Necessarily, investigation of the possibility of constitutive equations assumed to be of differential equation shape leads to the conclusion that, in addition to the assumed functions, the constitutive equations contain also so-called intrinsic variables. In conventional material testing, the use of intrinsic variables permits a constitutive equation taking into consideration also the dynamic load to be written
THE GENERALIZED PRINCIPLE OF VIRTUAL WORK
When the virtual work is considered as a time integral of
virtual power, a generalized form of the virtual work principle
is obtained. The Euler-Lagrange equation of it gives an equation for the
divergence of the Truesdell rate of stress. The equation of motion on the
stress rate field is one of the results of this paper
INVESTIGATION OF THE MECHANICAL BASIC EQUATIONS OF SOLID BODIES BY MEANS OF ACCELERATION WAVE
The basic equation of solid bodies experiencing minor deformation can be written after
the constitutive equation has been determined. This study outlines a new theory of determining
the constitutive equations, permitting new experimental methods to be set up on this basis
THE POSSIBLE FUNDAMENTAL EQUATIONS OF THE CONTINUUM MECHANICS
The possible fundamental equations are looked for in cases of infinitesimal and finite strain
based on the investigation of the acceleration wave. It is shown that also the selection of
the kinematical equations has an important role besides the constitutive equation
Conditional Lagrange Derivative with Gibbs Function
In forming constitutive relations a method of Mindlin was used. By introducing the conditional Lagrange derivative and by using the laws of thermodynamics a formula is obtained for ε. In the first law Gibbs function is used. This formula should be satisfied in case of constitutive relation
Nemlokális kontinuummechanika konstitutiv egyenletei, azok alkalmazása a nemlineáris hullám stabilitásvizsgálatban és a biomechanikában az érfal modellezésére = Constitutive equations of nonlocal continuum mechanics and their application on investigation of wave stability and in biomechanics on modelling of blood-vessel
A nemlokális testek anyagtörvĂ©nyeinek a szakcikkekben 8-fĂ©le felĂ©pĂtĂ©si mĂłdját találtuk. A lehetĹ‘sĂ©gek viszonylag nagy száma miatt arra következtettĂĽnk, hogy a nemlokális testek anyagtörvĂ©nyĂ©nek nincs elfogadott alakja. A felvetett 8 felĂ©pĂtĂ©si mĂłdbĂłl a kutatás során kettĹ‘t vizsgáltunk rĂ©szletesen, mĂ©gpedig a Mindlin-fĂ©le anyag esetĂ©t Ă©s a hullámdinamikai anyagtörvĂ©ny meghatározási mĂłdot. A kapott eredmĂ©nyek arra vezetnek, hogy a feszĂĽltsĂ©g tenzor egy funkcionál Lagrange deriváltja. BevezettĂĽk a feltĂ©teles Lagrange deriváltat, amely biztosĂtja a hullámdinamikai elmĂ©let által megkövetelt gyorsuláshullám lĂ©tezĂ©sĂ©t. Az ilyen Lagrange derivált a nemlokális test általánosabb alakjat Ă©rtelmezi. Az anyagi instabilitás kutatása a dinamikai rendszerek elmĂ©letĂ©ben kidolgozott mĂłdszerek alkalmazását teszi lehetĹ‘vĂ©. A feladatban ilyen mĂłdon a Ljapunov-fĂ©le vizsgálati mĂłdszerek felhasználásával az anyagtörvĂ©ny Ăşjabb lehetsĂ©ges változĂłi jelennek meg azonfelĂĽl, hogy tisztázhatĂł a bifurkáciĂłelmĂ©let felosztásainak egyĂ©rtelmű meghatározása, Ă©s ezek kapcsolata a nemlokális anyagtörvĂ©nyre vonatkozĂłan. A nem-lokális anyagok termomechanikai vizsgálata az irreverzibilis folyamatok esetĂ©n a termodinamikai Ă©s a mechanikai hullámok kĂĽlön-kĂĽlön Ă©s egyĂĽttes megjelenĂ©sĂ©t is eredmĂ©nyezi. A kĂ©trĂ©tegű vastagfalĂş csĹ‘ alkalmas modell a meszesedĹ‘ vĂ©rerek szilárdsági megĂtĂ©lĂ©sĂ©re. A modellt finomĂtottuk a nemlokális testek esetĂ©re, amely a meszesedĹ‘ erek szerkezetĂ©nek pontosabb figyelembevĂ©telĂ©t tette lehetĹ‘vĂ©. | In the literature of the constitutive equations of nonlocal bodies eight types of possible constructions can be found. The large number of possibilities implies that there is no generally accepted form for nonlocal bodies. In the studies performed we consider two out of the eight, namely the case of Mindlin's material and the use of the wave dynamical method. The results show that the stress tensor is a Lagrange derivative of a functional. By introducing the conditional Lagrange derivative the existence of the acceleration wave is obtained. Such wave is necessary for the wave dynamical method. This Lagrange derivative defines a more general form of the nonlocal body. The investigation of material instability enables us to apply the tools of the theory of dynamical systems. I such a way by using Lyapunov's methods additional possible variables of the constitutive equation can be detected. Moreover, we can clarify the connection of the classification of bifurcation theory and the nonlocal constitutive equations. In case of irreversible processes the thermo-mechanical investigation of nonlocal bodies results the appearance of thermodynamic and mechanical waves as both separate and coupled phenomena. The thick walled tube of dual layer is an appropriate model for studying blood vessels under arteriosclerosis. This model can be refined for nonlocal bodies, which enables us to get a more exact consideration for the structure of the arteriosclerosis effect
THE EQUATION OF MOTION OF MECHANICAL SYSTEMS BASED ON D'ALEMBERT-LAGRANGE'S EQUATION
The equations of motion of mechanical (discrete or continuous) systems can be deduced
from d'Alembert-Langrange's equation. The equation of motion of micropolar body is
obtained on the continuous bodies. More conclusions and questions are given from the
presented arithmetic