In several industrial sectors, there are continuous requirements to develop lighter materials for various loading situations. The special process for achieving it is mainly the use of composite sandwiches where two skins are glued or printed on an architectural core. In this article, the static behavior and the failure mechanisms in sandwich composite with anti-trichiral architecture are studied. The core and the sandwiches are made from the same bio-based material which is polylactic acid PLA with short flax fibers. A Raise3D Pro2 Plus printer is used to elaborate the tested specimens. Several tensile tests are carried out on the anti-trichiral core while bending tests are performed on the sandwich structures. Those tests are conducted on specimens of the metamaterial for different node radius of the anti-trichiral unit cell in order to study their effect on the static properties of this architectured material and the damage characteristics of the sandwiches. Acoustic emission technology (AE) is used to monitor and quantify the failure mechanisms of sandwich materials. The results show that the structural Poisson’s ratio and the Young’s modulus of the anti-trichiral cores largely depends on the radius (r) of the round nodes of the unit cell.