Intra-band gap in Lamb modes propagating in a periodic solid structure

摘要: A laser ultrasonic technique is used to measure the dispersion of Lamb waves at a few MHz, propagating in phononic crystals made dissymmetric air inclusions drilled throughout silicon plates. It shown that specific shape origin intra-band gap opens within second Brillouin zone, crossing both flexural and dilatational zero-order modes. The magnitude measured as function dissymmetry rate inclusions. Experimental data computed curves are very good agreement.