# Research on the Elastic Loss Characteristics of Acoustic Echoes from Underwater Corner Reflector

## TL;DR

This paper studies how elastic loss in acoustic echoes from underwater corner reflectors affects their performance, showing that they behave differently from rigid structures.

## Contribution

The study introduces a method combining finite element and boundary element analysis to investigate elastic loss in underwater corner reflector echoes.

## Key findings

- Underwater corner reflectors exhibit elastic loss characteristics in their acoustic echoes.
- Elastic loss reduces target strength, narrows directional patterns, and destabilizes frequency.
- Elastic loss is consistent across single-grid and multi-grid corner reflectors.

## Abstract

The underwater corner reflector is a “concave” elastic structure, and its acoustic echo exhibits large elastic loss, which affects its practical use. To study the acoustic echo elastic loss characteristics of underwater corner reflectors, based on the characteristics of small concave elastic structures of underwater corner reflectors, theoretical calculations were performed using the method of a combination of finite element and boundary element. Taking the underwater rigid corner reflector as the benchmark, the acoustic echo differences between similar types of underwater elastic corner reflectors were compared. The regular acoustic echo elastic loss of underwater corner reflectors was analyzed, and verified through pool experiments. The results show that, whether single-grid or multi-grid corner reflector, the actual acoustic echoes of underwater corner reflectors conform to the characteristics of elastic bodies, which differ significantly from rigid bodies and exhibit obvious elastic loss. The elastic loss mainly manifests as reduced target strength (TS), narrower directional pattern width, and poorer frequency stability of target strength, which is detrimental to practical use. This study provides assistance in proposing targeted methods to suppress elastic loss.