A moldable composite with high heat resistance and noise absorption properties utilizes nonwoven fabrics and a heat resistance additive. The composition that provides both superior acoustic performance and excellent flex modulus that may be utilized in automotive products and applications in interior and exterior structures. A blowing agent may be utilized to create micro porous cells in a polymer non-woven structure. The cells or voids make the material lighter and allow the material to have superior acoustic properties that are useful in automotive applications.

A method for manufacturing a multi-perforated acoustic skin out of composite material for an acoustic attenuation structure, the method including forming a fibrous preform including a matrix precursor material, carrying out a heat treatment for transforming the precursor into a matrix so as to obtain a multi-perforated acoustic skin made of composite material including a fibrous reinforcement densified by the matrix, the forming of the fibrous preform including draping fibers on a surface of a mandrel including protuberances, and the mandrel and the protuberances can be each made of a material that melts at a temperature lower than the heat-treatment temperature for transforming the precursor into a matrix in such a way as to eliminate the mandrel and the protuberances during the transforming heat treatment step.

A method is provided for manufacturing. During this method, a first woven fiber sleeve is disposed over a first mandrel to provide a first overbraided mandrel. The first woven fiber sleeve is wrapped circumferentially around the first mandrel. An opening is formed through a side of the first woven fiber sleeve. A second woven fiber sleeve is disposed over a second mandrel to provide a second overbraided mandrel. The second woven fiber sleeve is wrapped circumferentially around the second mandrel. The second overbraided mandrel is arranged with the first overbraided mandrel. The second woven fiber sleeve engages the side of the first woven fiber sleeve. A second overbraid first end is disposed at and extends circumferentially around the opening. A polymer material is disposed with the first woven fiber sleeve and the second woven fiber sleeve to provide a duct structure.

There is provided a polyurethane foam, wherein at least one of principal surfaces opposite to each other has a hole opening ratio of 0% to 1.0%, and the principal surface having the hole opening ratio has a root mean square surface roughness of 0.01 to 0.30 m in accordance with JIS B 0601:1994, and the polyurethane foam has an air permeability of 0 to 2.0 cm.sup.3/cm.sup.2/sec in accordance with JIS K 6400.

A method of fabricating a binary metasurface for producing an ultrasound Airy beam for underwater ultrasound applications is provided. The method includes generating an amplitude distribution of an Airy beam at a frequency, and converting the amplitude distribution into a binary phase profile. The method also includes generating a 3D printing design of a binary metasurface based on the binary phase profile, wherein the binary metasurface includes ridges and grooves defined by neighboring ridges, a ridge having a thickness corresponding to a phase delay of /2 of the Airy beam between water and a 3D-printable material. The method further includes additively manufacturing the binary metasurface with the 3D-printable material based on the 3D printing design.