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Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins(trusses) into a foam matrix to create a truss-like network reinforced foam core.Upon loading,the pins deform predominantly by local stretching whilst the deformation of foam is governed by local bending.This paper presents a theoretical study on the thermoelasticity of pin-reinforced foam sandwich cores.To calculate the effective thermoelastic properties of pin-reinforced foam cores,the energy-based homogenization approach is employed to develop a micromechanics-based model,calibrated by the existing experimental data.It is found that the stiffness of the sandwich core is mainly governed by pin reinforcements:the foam matrix contributes little to sandwich stiffness.Compared with traditional foam cores without pin reinforcements,the changes in inplane thermal expansion coefficients are not vigorous as a result of pin reinforcements,while the through-thickness thermal expansion coefficient changes significantly.It is also demonstrated that it is possible to design materials with zero or negative thermal expansion coefficients under such a context.
Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins (trusses) into a foam matrix to create a truss-like network reinforced foam core. ??? loading, the pins deform predominantly by local stretching whilst the deformation of foam is governed by local bending. This paper presents a theoretical study on the thermoelasticity of pin-reinforced foam sandwich cores. To calculate the effective thermoelastic properties of pin-reinforced foam cores, the energy-based homogenization approach is employed to develop a micromechanics-based model , calibrated by the existing experimental data. It was found that the stiffness of the sandwich core is mainly governed by pin reinforcements: the foam matrix contributes little to sandwich stiffness. Compared with traditional foam cores without pin reinforcements, the changes in inplane thermal expansion coefficients are not vigorous as a result of pin reinforcements, while the through-thickness thermal expansion coefficient changes sig nificantly.It is also for that it is possible to design materials with zero or negative thermal expansion coefficients under such a context.