Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of fragments.Attention is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of fragments.The results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural parameters.In this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

Short beam shear properties and failure modes of the wood-based X-type lattice sandwich structure

A wood-based X-type lattice sandwich structure was manufactured by insertion-glue method.The birch was used as core,and Oriented Strand Board was used as panel of the sandwich structure.The short beam shear properties and the failure modes of the wood-based X-type lattice sandwich structure with different core direction(vertical and parallel),unit specification(120 mm×60 mm and 60 mm×60 mm),core size(50 mm and 60 mm),and drilling depth(9 mm and 12 mm)were investigated by a short beam shear test and the establishment of a theoretical model to study the equivalent shear modulus and deflection response of the X-type lattice sandwich structure.Results from the short beam shear test and the theoretical model showed that the failure modes of the wood-based X-type lattice sandwich structure were mainly the wrinkling and crushing of the panels under three-point bending load.The experimental values of deflection response of various type specimens were higher than the theoretical values of them.For the core direction of parallel,the smaller the unit specification is,the shorter the core size is,and the deeper the drilling depth is,the greater the short beam shear properties of the wood-based X-type lattice sandwich structure is.

Parametric Vibration Stability Analysis of a Pyramid Lattice Sandwich Plate Subjected to Pulsatile External Airflow

Lattice sandwich structures are broadly used in aerospace,navigation,and high-speed rail engineering.In engineering practice,the airflow outside the vehicle or aircraft always exhibits the pulsatile property,which makes the elastic structural components and the external airflow a parametric excitation system.In this paper,the parametric vibration stability analysis and dynamic characteristics of a lattice sandwich plate interacting with the pulsatile external airflow are studied.The equation of motion is derived using Hamilton’s principle and discretized using the assumed mode method.The linear potential flow theory is applied to derive the perturbation aerodynamic pressure.The stability of the system is analyzed using the Floquet theory and validated by numerical simulations.The effects of design parameters of the lattice sandwich plate on the stability of the system are discussed.From the simulations and discussions,some practical principles for the optimal design of lattice sandwich structures in the aerodynamic environment are proposed.