Abstract
In this work, we constructed a mathematical model of an infinite elastic body with a spherical cavity in the context of the theory of generalized thermoelasticity with fractional order strain. The bounding plane of the cavity is connected with thermal shock. Laplace transform techniques are used, and the inversions are computed numerically using a method based on Fourier expansion techniques of Tzuo method. Some especial comparisons have been illustrated in figures to discuss the effects of the two-temperature and the fractional order parameters.
Introduction
The cartilage is a being part of the human quantity where it is a connective tissue that furnishes the rework for most of the junction in the body open a multi-ladder building that harnesses an extended order of single collagen and molecules to families of twisted macromolecular fibers and fibrils. To disentangle several-scatter modeling drive that prizes the macro-scale mechanical a quittance of cartilage from the micro-spread standard is the censure of the bioengineer so that this novel model will help them [1]. Fractional order Voigt standard performed better obtain to the integer direction models so, the unfolding recite here will help in better knowing the viscoelastic properties of soft human tissue and may direct to amended diagnostic applications [1]. Magin and Royston invent the first fork in which fractional calculus with the model of the insignificant usage sprain that characterizes the momentous action has been attaching. In this pattern, the compound with zero order is for a Hookean true and to one for a Newtonian fluid while the stretchable and the viscoelastic materials busy the order with a fractional order parameter between zero and one [1].
Youssef built the hypothesis, speculation of two-temperature generalized thermoelasticity with the general uniqueness theorem [2]. Youssef also derived a new theory of two-temperature generalized thermoelasticity theory for an isotropic and homogeneous thermoelastic body without energy dissipation [3] and induced the variational principle of this model [4].
Youssef derived a novel hypothesis of thermoelasticity supported on fraction order of sprain which is estimated as a new modification to Duhamel-Neumann of stress-strain description. After setting the equations which direct this speculation, Youssef explains the first applications of thermoelasticity with fractional order strain for one-dimensional and thermoelastic half-space based on different models of thermoelasticity [5]. Bassiouny and Youssef studied the thermoelastic behavior of a sandwich structure subjected to a thermal shock in context of generalized thermoelasticity with fractional order strain in the presence of a moving heat source [6]. Abbas has solved many problems in the context of two-temperature thermoelasticity theory [7, 8, 9, 10, 11].
In this paper, we will solve a mathematical model of an infinite thermoelastic body with a spherical cavity based on the theory of generalized thermoelasticity with fractional order strain. The bounding surface of the cavity is affected by a thermal shock. Laplace transform techniques will be applied, and the inversions will be computed numerically using a method based on Fourier expansion techniques of Tzuo iteration method.
The Governing equations
The equation of motion without body force takes the form [12]:
The constitutive equation takes the form [5]:
The heat conduction equation takes the form [5]:
Where the fractional derivative with respect to the time
The relation between the heat conduction and the dynamical heat takes the form [13]:
where
We will suppose elastic and homogenous infinite body with a spherical cavity with radius
The strain component takes the form
and
Hence, we have
The equation of motion takes the form
The constitutive equations take the forms
and
The heat conduction equation takes the form ,
The relation between the heat conduction and dynamical heat takes the form
where
Equation (10) could be written as follows:
For simplicity, we will use the following non-dimensional variables [15, 16]:
where
Hence, after dropping the primes, we have
Multiply Eq. (18) by
The heat equations take the forms
and
Equations (11) and (12) take the forms:
and
where
Applying the Laplace transform for both sides of the Eqs (18)–(22), this is defined as follows:
Hence, we obtain
where the rule for the Laplace transforms of the Riemann-Liouville fractional derivative, reads from [17]:
where the initial conditions are:
From Eqs (24) and (25), we get
where
Substituting from Eq. (31) into Eqs (23) and (24), we obtain
and
where
From Eqs (32) and (33), we have
The general solution of Eq. (34) takes the forms
and
where
Hence, we have the following relations
In the Eqs (34) and (35) the positive powers of the expositions have been canceled to make the solutions bounded fora considerable value of
To get the values of the parameters
Applying Laplace transform, we have
Moreover, we consider also that the bounding plane of the cavity
Applying Laplace transform, we obtain
Hence, we have the following system:
and
The conductive temperature distribution.
The dynamical temperature distribution.
Solving the system on Eqs (40) and (41) gives
Finally, we have the solutions as follows:
We consider the thermal loading of the bounding surface of the cavity in the thermal shock form as follows:
where
Hence, we have
which complete the solution in the Laplace transform domain.
The solutions in the time domain and the numerical results can be calculated by using the Riemann-sum approximation method. Any function in Laplace domain can be inverted to the time domain as [18]:
where Re is the real part and is imaginary number unit. For faster convergence, many results of numerical experiments shown that the value of parameter
The copper significant was preferred for the aim of numerical evaluations, and the constants of the proposition were taken as follows [6, 12, 14, 15, 16, 19]:
K
The computations were carried out for the non-dimensional time
The conductive temperature, the dynamical temperature, the strain, the displacement, and the radial stress are represented graphically with various values of the non-dimensional distance
Figures 1 and 2 represent the conductive and the dynamical temperature, respectively, for the one-temperature (
Figures 3–5 represent the strain, the displacement, and the radial stress, respectively, for the one-temperature (
The strain distribution.
The displacement distribution.
The radial stress distribution.
Figures 6 and 7 represent the conductive and the dynamical temperature, respectively, for the two-temperature model (
The conductive temperature with various fraction order parameter.
The dynamical temperature with various fraction order parameter.
Figures 8–10 represent the strain, the displacement, and the radial stress, respectively, for the two-temperature model (
The strain with various fraction order parameter.
The displacement with various fraction order parameter.
The radial stress with various fraction order parameter.
A mathematical model of an infinite elastic body with a spherical cavity in the context of the theory of generalized thermoelasticity with fractional order strain has been constructed. The medium is assumed initially quiescent, and the bounding plane of the cavity is subjected to thermal shock. The results of this work show that the fractional order parameter and the two-temperature parameter have significant effects on the thermal and the mechanical waves.
