Dynamic Sonar Mount
Applied Physics Lab
August 2022
CUI: Some details & drawings cannot be shared
Objective
As a final project at the APL (Applied Physics Lab), I was tasked with designing and manufacturing a mounting solution that could secure a specific research sonar in an operational position while attached to the densely component-packed submersible truss on the testing vessel. This truss is operated by being lowered from its dry, storage/modifiable position into the water during operation. Given the little available space to attach this sonar, the main design challenge became devising a design that could store itself in a compact configuration, while needing to change the orientation of the sonar to be functional during operation.
Full assembly shifting between the storage position and the angled, operational position. The shoulder bolts keep the floating clamping mechanism on track and tighten in to lock the assembly in place.
Design Features
- Easy to assemble and break down for extended storage
- 3D-printed clamps tightening using bolts & threaded heat inserts
- Each part in the assembly is low-cost, simple to manufacture, and easily replicable/replaceable
- Simple & secure transition between operation and storage
- Only requires hand tightening of shoulder bolts, avoiding the hassle of using heavy & slippery metal tools that are easily dropped into the water
- Several important cutouts and fillets to reduce drag forces on the mount during operation as the assembly is pulled through the water
- Avoids excessive vibration would drastically lower the resolution & reliability of the sonar
Inserting a threaded heat insert into the 3D print
Challenges
Given the structure and configuration of components on the submersible truss, there was no static solution in which the sonar could rest safely within the boundaries of the truss and operate without interference from other components or the truss frame.
L-3 Communications SeaBeam Instruments. (2000). Multibeam Sonar Theory of Operation. p. 20
Sonar beam interference refers to an obstruction of the path of the sonar sound waves by other surrounding objects. This beam form is shown in the image above. With no static solution, I decided to create a mount that could easily transfer between operational and storage positions without adding much complexity to the user. This created another benefit in that the sonar array face was also more protected through this design.
This mount had to be able to survive extended amounts of time submerged underwater (fresh/saltwater) as well as dry storage out of the water. This played a large role in material selection. The mount hardware is made out of aluminum and corrosion-resistant stainless steel and the 3D-printed parts are made out of Zortrax Z-ULTRAT filament.
Key Takeaways
- More complex 3D printing techniques & experience (ex. heat inserts)
- Designing a secure, multi-material, well-toleranced dynamic assembly
- Communication with machine shop to produce a part