Lattice Truss Core Research Articles

Mechanical Response of All-composite Pyramidal Lattice Truss Core Sandwich Structures

The mechanical performance of an all-composite pyramidal lattice truss core sandwich structure was investigated both theoretically and experimentally. Sandwich structures were fabricated with a hot compression molding method using carbon fiber reinforced composite T700/3234. The out-of-plane compression and shear tests were conducted. Experimental results showed that the all-composite pyramidal lattice truss core sandwich structures were more weight efficient than other metallic lattice truss core sandwich structures. Failure modes revealed that node rupture dominated the mechanical behavior of sandwich structures.

Optimal design of box-section sandwich beams subject to moving load

Minimum weight designs of sandwich beams subject to moving load are performed as a function of prescribed load index, where the stiffness and strength constraints are both considered. The dynamic properties of sandwich beams are detected and validated through finite element simulation. Five different topologies are optimized and compared. Numerical results show that the topology of a hollow tube with sandwich walls comprising a lattice tetrahedral truss core is the most weight efficient, whereas the topology of a hollow tube with monolithic walls and a foam-filled core is the heaviest. The failure mechanisms that govern the optimal designs are also evaluated. The optimal results exhibit great sensitivity to the load moving velocity when it approaches the critical velocity of the sandwich beams. The optimization for sandwich beams under three-point bending is implemented for comparison and special dynamic characteristics of sandwich beams subject to moving load are discovered.

Mechanical behavior of the sandwich structures with carbon fiber-reinforced pyramidal lattice truss core

Sandwich panel construction with carbon fiber-reinforced pyramidal lattice truss is attracting more and more attention due to its superior mechanical properties and multi-functional applications. Pyramidal lattice truss sandwich panels made from carbon fiber reinforced composites materials are manufactured by hot-pressing. The facesheets are interconnected with truss cores, the facesheets and truss cores are manufactured in one manufacturing process without bonding. The buckling and splitting of truss member is observed in the compressive and shear tests and no nodal failure is observed. The predicted results show that the mechanical behavior of the pyramidal lattice truss core sandwich panels depends on the relative density of core and the material properties of truss members.

Compressive strength of tube-woven Kagome truss cores

We tried to fabricate lattice truss structure cores from SUS 304 stainless steel tubes. The compressive behaviors of the cores were investigated. The micro- and macro-structures and failure mechanisms under compression were observed. It was seen that the tube-woven lattice truss structures could be fabricated from the tubes without any technical difficulty, although the process involved the helical formation of the tubes. The compressive strengths of the tube-woven lattice truss cores were found to be higher than those predicted by analytical solutions. The post-peak behavior was stable and wavy, thus absorbing sufficient energy before the final densification. The tube-woven lattice truss cores outperform most cellular metals except for hollow trusses.

Shear behavior of aluminum lattice truss sandwich panel structures

Age hardenable 6061 aluminum tetrahedral lattice truss core sandwich panels have been fabricated by folding perforated sheets to form highly flexible cellular cores. Flat or curved sandwich panels can be fabricated by furnace brazing the cores to facesheets. Flat sandwich panels with core relative densities between 2 and 10% have been fabricated and tested in the σ ±13 shear orientation (minimum shear strength orientation for a tetrahedral lattice) in the fully annealed (O) and aged (T6) conditions. The shear strength of the lattices increased with relative density, parent alloy yield strength and work hardening rate. Analytical stiffness and strength predictions agree well with measured values for all relative densities and parent alloy heat treatments investigated. The stiffness and strength of 6061-T6 aluminum tetrahedral lattice structures are shown to be comparable to those of conventional 5052-H38 aluminum closed cell hexagonal honeycombs and more than 40% stiffer and stronger than flexible honeycombs used for the cores of curved sandwich panels.

Compressive behavior of age hardenable tetrahedral lattice truss structures made from aluminium

Open cell, lattice truss structures have been made by folding perforated 6061 aluminium alloy sheets. Simple air brazing is used to construct sandwich panels with cellular core relative densities between 0.02 and 0.08. Some panels were quenched and aged while others were tested in an annealed condition. The measured peak compressive strengths varied from 0.7 to 20 MPa, increasing with core relative density and parent alloy yield strength. The peak strength of the annealed lattice significantly exceeds ideal-plastic predictions. A model based on inelastic column theory incorporating strain hardening was able to predict the lattice truss core's compressive peak strength capacity in both the annealed and age hardened conditions, for all relative densities tested. Comparisons with compressive strength data for other cellular metals indicate that wrought aluminium alloy tetrahedral lattice structures outperform aluminium foams and prismatic corrugations, and compare favorably with honeycombs when the strain hardening of the parent alloy is high. Their impact energy absorption can be similarly tuned and competes well with other concepts under high intensity loading conditions.