Nonlinear thermo-structural behavior of sandwich panels with truss cores under through-thickness gradient temperature field

A theoretical analysis is presented to predict the nonlinear thermo-structural response of metallicsandwich panels with truss cores under through-thickness gradient temperature field, which is acommon service condition for metallic thermal protection system （TPS）. The in-planetemperature distribution is assumed to be uniform, and through-thickness temperature field isdetermined by heat conduction. Two typical conditions are analyzed： nonlinear thermal bendingin fixed inside surface temperature, and thermal post-buckling in fixed temperature differencebetween two surfaces. Temperature-dependent mechanical properties are considered, andgradient shear stiffness and bending stiffness due to non-uniform temperature is included. Resultsindicate that the temperature-dependent material properties obviously affect bending resistance;however, the effect is negligible on post-buckling behavior. Influences of geometric parameters onthe thermo-structural behavior of the sandwich panel according to the present theoretical modelare discussed.

Cantilever sandwich beams with pyramidal truss cores subjected to tip impact

Experiments were conducted to investigate the deformation of cantilever sandwich beams with pyramidal truss cores subjected to impact by a projectile at their tips.A new technique was employed to the fabrication of sandwich beams with pyramidal truss cores.For a better observation of large deformation of specimens during impact process,a high-speed digital video camera was successfully used to capture the instant shapes of the deformed beams.A projectile collection device was designed and installed to avoid the projectile flying away from the beam tips after impact and thus the kinetic energy imparted to the beams was measurable.The experiments show that the sandwich beams have a superior shock resistance compared to the monolithic beams of the same material and mass.Further,finite element simulations were performed to gain insight into the deformations and plastic energy absorptions in the sandwich beams.

Fabrication and Testing of Carbon Fiber Reinforced Truss Core Sandwich Panels

Truss core sandwich panels reinforced by carbon fibers were assembled with bonded laminate facesheets and carbon fiber reinforced truss cores. The top and bottom facesheets were interconnected with truss cores. Both ends of the truss cores were embedded into four layers of top and bottom facesheets. The mechanical properties of truss core sandwich panels were then investigated under out-of-plane and in-plane compression loadings to reveal the failure mechanisms of sandwich panels. Experimental results indicated that the mechanical behavior of sandwich structure under in-plane loading is dominated by the buckling and debonding of facesheets.

Sound Insulation Performance of Pyramidal Truss Core Cylindrical Sandwich Structure

Recently,cylindrical structures have been exploited in various fields due to their excellent mechanical properties.With the increase in the application of cylindrical shell structures,researchers are paying more and more attention to its acoustic performance and sound insulation applications.By inserting the pyramidal truss lattice into the cylindrical shell structure,a cylindrical sandwich structure is obtained and the sound insulation performance of the structure is investigated.The space-harmonic expansion method and the principle of virtual work are employed to establish a theoretical model for the acoustic analysis of cylindrical sandwich structures.The vibro-acoustic coupling is taken into account by imposing the velocity continuity condition at the fluid-solid interface.The sound transmission loss(STL)performance of the structure is examined by establishing both theoretical and finite element models.Subsequently,the influence of various parameters on sound transmission loss is researched and analyzed.