Acoustic Reflector Shell Core Design
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Solution Overview
Problem
Existing acoustic reflectors face challenges such as core material cracking during manufacture, difficulty in detecting underground gas pipes, and issues with water ingress leading to catastrophic failure when brought to the surface, along with cumbersome manufacturing methods that are not suitable for solid or cured core materials.
Innovation Solution
The development of an acoustic reflector with a shell surrounding a join-free solid core, where the shell is made of materials like glass fibre reinforced polyphthalamide or aluminium, and the core is filled with materials like butyl rubber or silicon elastomer, allowing for improved sound wave transmission and reflection, and a manufacturing process involving spin welding of hemispherical shells to prevent air pockets and fissures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elastomer core is cast into shell halves and glued together, then manufacturing is easier, but core cracking occurs during manufacture
Solution Approach 1:
The shell is divided into two separate halves that are joined together, allowing the core to be filled in a single piece without requiring complex molding operations. This segmentation enables easier manufacturing while maintaining core integrity by avoiding the need to cast through the entire shell structure.
Solution Approach 2:
The core is filled with liquid elastomer before the shell halves are joined together. This preliminary action allows the core material to be introduced in a controllable state, preventing cracking that would occur during or after the joining process.
2Ease of operation
If conventional electromagnetic detection systems are used, then detection of underground objects is easier, but gas pipes and non-conductive objects cannot be detected
Solution Approach 1:
An acoustic reflector is introduced as an intermediary device attached to the gas pipe. This reflector converts the non-detectable gas pipe into a detectable acoustic target by reflecting sound waves, enabling detection systems to locate the pipe without direct electromagnetic interaction.
Solution Approach 2:
The detection method is substituted from electromagnetic fields to acoustic wave reflection. By attaching an acoustic reflector to the gas pipe, the system uses mechanical sound wave reflection instead of electromagnetic detection, enabling detection of non-conductive objects.
3Ease of manufacture
If shell and core are glued together, then assembly is simpler, but water ingress leads to catastrophic failure
Solution Approach 1:
The shell halves are joined together using spin welding to create a seamless, integrated structure. This merging eliminates gaps and joints that would allow water ingress, providing reliable water resistance while maintaining manufacturing efficiency.
Solution Approach 2:
The joining method is substituted from chemical bonding (gluing) to mechanical bonding (spin welding). This replacement provides superior water resistance by creating a continuous, gap-free joint that prevents water ingress, while still being efficient to manufacture.
4Reliability
If aluminium shell is used, then acoustic transmission is improved, but shell strength is reduced
Solution Approach 1:
The shell is constructed from composite materials that combine the acoustic transmission properties of aluminium with the strength characteristics of other materials. This composite structure achieves both improved acoustic transmission and maintained shell strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances acoustic reflection performance, reduces the risk of core cracking, and allows for efficient detection of underground objects, while the spin welding method ensures structural integrity and prevents water ingress-related failures, making the reflectors suitable for various applications including underwater marking and navigation.
Implementation Method 1
said shell having one or a plurality of acoustic windows through which acoustic waves incident on the surface of the shell are transmitted into the core
Implementation Method 2
in which acoustic waves entering the core are reflected from the interior of the shell opposite the window(s) back towards and through the window(s)
Implementation Method 3
The two shell halves are spin welded together
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
An acoustic reflector (10) comprises a shell (12) surrounding a core (16), said shell (12) being capable of transmitting acoustic waves incident on the surface of the shell (12) into the core (16) to be focused and reflected from an area of the shell (12) located opposite to the area of incidence so as to provide a reflected acoustic signal output from the reflector (10), having a core (16) in which the shell (12) is dimensioned relative to the core (16) such that a portion of the acoustic waves incident on the shell wall are coupled into the shell (12) and guided therein around the circumference of the shell (12) and then re- radiated to combine constructively with the said reflected acoustic signal output so as to provide an enhanced reflected acoustic signal output. The ratio of the speed of sound wave transmission in the shell to the average speed of the wave transmission in the core is preferably in the range of 2.74 to 3.4, inclusive with best result in the range of 2.74 to 2.86 inclusive.