Simulation of the coupled thermo-elastic behaviour of constrained films in differential scanning calorimetry using the finite element method

• Published in: Thermochimica acta Vol. 581; pp. 62 - 69
• Main Authors: Repka, M., Lion, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10-04-2014
• Subjects: Calorimetry; Computer simulation; Constraints; Finite element method; Joining; Mathematical analysis; Mathematical models; Specific heat; Thermal expansion; Thermoelasticity; Thin films; Finite element method; Thin films; Specific heat; Thermal expansion; Calorimetry; Thermoelasticity
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2014.02.010

•The behaviour of the thermo-elastic film in DSC device is studied for different values of the coefficients of thermal expansion.•The specific heat is calculated on the basis of FEM solution of fully coupled thermo-elasticity.•The thermal flux emitted to the film depends on the stress in the substrate.•The calculated specific heat of the film varies according to the sign of the stress in the substrate.•The validity of the analytical formula is confirmed.
In [1], the thermo-elastic approach developed in [2] has been applied to model the calorimetric behaviour of thin polymer films which are deposited on metal substrates. The expression to calculate the specific heat of the constrained film was derived. In the current paper, this approach will be validated by the numerical simulation of the related boundary value problem. With the finite element solution of the fully coupled thermo-elasticity problem using the software COMSOL, the specific heat of the constrained film is simulated for different types of thermal expansion behaviour. It is shown that the specific heat of the film depends on the thermal strains which are induced in the substrate. The lateral stresses in the film can be negative or positive according to the difference in the thermal expansion coefficients between the film and the substrate. It is shown that due to the transformation of energy from thermal into mechanical forms or vice versa the heat supplied to the pan of the DSC-device can be different and consequently influence the specific heat. The heat flux which is going into the film for different coefficients of thermal expansion is numerically simulated. The validity of the expression derived in [1] is also confirmed.