Thermal-mechanical Coupling Effect Research Articles

Trans-scale modeling framework for failure analysis of cryogenic composite tanks

The mechanical performances of cryogenic composite tanks need strict evaluation due to its extreme temperature condition of service. In this paper, a trans-scale modeling strategy is developed for the failure analysis of cryogenic composite structures, which is based on theories from micromechanics to continuum mechanics. Micromechanical model of representative volume element is developed to obtain the thermo-mechanical coupling properties of materials in the composite structure. Continuum mechanics model is sub-sequentially developed to predict the fields of physical properties in the composite structures. The predictions of performances of composite structures at cryogenic and different temperatures are of good agreement with conventional theoretical solutions. Numerical examples of cryogenic composite tanks indicate that the large temperature change can directly cause the fracture of matrix that can result in the overall failure of composite tanks. In addition, the thermal–mechanical coupling effect can reduce the prediction of critical thermal loads in the failure analysis of cryogenic composite tanks, which is more favorable for engineering designs due to the strict requirements of safety.

A Novel Constitutive Formulation for Rubberlike Materials in Thermoelasticity

The objective of this paper is to present a new framework to formulate thermoelastic constitutive relations for initially isotropic rubberlike materials undergoing finite deformations. The strain-energy function for incompressible materials is extended to include the effects of compressibility and temperature changes. The novelty of this framework is that only a few material functions and material parameters to be fitted with the experimental data are required, and these functions and parameters have clear physical meaning. In order to validate the proposed formulation, the Gent–Gent model for incompressible rubbers is chosen as an illustrative example. A new expression of the Helmholtz free energy of rubberlike materials, which takes into account the material compressibility and thermal effect, is then derived. In this generalized Gent–Gent model, only one material function and six material parameters are introduced. It is shown that the generalized Gent–Gent model can be used to predict the stress-strain behavior over the entire range of deformation. Even for incompressible materials, the strain-energy function in this paper is different from that given by Gent himself. The generalized Gent–Gent model can also adequately describe the thermal-mechanical coupling effect, in which thermoelastic inversion phenomena occur.

Effects of cutting parameters on surface residual stress and its mechanism in high-speed milling of TB6

Formation mechanism and influence of cutting parameters on residual stress in flank milling of TB6 are investigated through orthogonal experiments. The thermal–mechanical coupling effect on forming residual stress is studied by analyzing the microstructure of metamorphic layer. Experiment results show that cutting temperature varies between 300 °C and 518 °C under experiment conditions, while residual compressive stress on machined surface is −199.8 to −41.7 MPa. Tensile residual stress occurs on subsurface when increasing milling parameters excessively. When cutting TB6 with parameters of fz = 0.02 mm/z, vc = 60 m/min, ae = 0.2 mm and ap = 10 mm, only the compressive residual stress can be detected, which is good for its fatigue life. The depth of compressive residual stress layer is 10–20 µm.

Investigation on Laser Etch-Machining Underwater Based on Thermal-Mechanical Effect

The method of high-energy short pulse laser etching underwater based on thermal - mechanical effect was put forward. In the experiment system with mask and salt solution , heat affected zone was visible decrease and the image of mask was micro-copied at the workpiece surface. Owing to the photochemical reaction and thermal-mechanical coupling effect, uniform line width of 120μm can be obtained.

Numerical simulation on the damage of buried thermal-pipeline under seismic loading based on thermal-mechanical coupling

The thermal-mechanical coupling effect is one of important factors in construction engineering, which will cause the buried thermal-pipeline to damage. So a three-dimensional finite element model is established based on ADINA-TMC, which considers thermal-mechanical coupling and seismic loading simultaneously. In this model, seismic loads and faults movement are defined. According to the numerical results, stresses and strains under gravity, seismic loading, and temperature load are compared, which provides theoretical method for failure analysis of buried thermal-pipeline.

Variational Principle of Carbon Nanotubes with Temperature Changes Based on Nonlocal Euler-Bernoulli Beam Model

In this paper, the CNTS are considered as the Euler-Bernoulli beams which have been used in many references about the CNTS. Taken the thermal-mechanical coupling and small scale effect into account, the variational principle for the CNTS is presented by the variational integral method. With the derivation of the varitional principle, the vibration governing equation is illustrated, which will be benefit for the numerical simulation with finite element method in further investigations. From the stationary value conditions deduced by the variational principle, the influences of the temperature changes and the thermal expansion coefficients based on nonlocal Euler-Bernoulli beam model are presented.