Laser speckle-based estimation of surface condition for designing quieter material

Laser speckle is a non-contact, non-interfering, non-destructive, rapid and controllable technique with a large area of coverage that has attracted much attention for surface analysis of materials. The emergence of different natural cellulosic materials as potential candidates for the replacement of synthetic ones is promising, but their sustainability from the point of view of material design is still in question. Machining of the surface of cellulosic components for making sound-dampening materials has a critical effect on determining their surface condition. Laser speckle is an emerging tool for surface analysis of a variety of materials, and it has important applications in material design and analysis. As a cutting-edge research tool, ultrasonic wave technology has maintained a significant contribution to the design and structural monitoring of composite materials. The present work uses date palm leaf fibers for composite reinforcement. The sound-dampening properties, such as sound absorption and transmission, were analyzed on the basis of surface roughness observed with the laser speckle technique and modified by ultrasonically blended surfactants. The surface roughness of the synthesized material was found to increase with sonication time with an R ² value of 0.944 and observed fluctuation in roughness data on the surface of the material. The sound absorption coefficient is 0.98 with a transmission loss of 60 dB, for which the material is classified as an ASTM E1050 Class A acoustic material. Further, the method of laser speckle-based roughness estimation is found to be potential tool for the design of any type of quieter material.