Composite Diaphragm Holder for Lightweight Compression Resistance
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Solution Overview
Problem
Existing diaphragm holders for oleopneumatic shock absorbers, particularly in aircraft landing gear, are heavy and costly due to traditional metal machining, and alternative thermoplastic polymers do not adequately address mechanical properties like compressive failure and dimensional constraints.
Innovation Solution
A method involving overmolding a thermoplastic polymer with fibers onto an insert, which can be metallic or polymer, to create complex geometries and enhance mechanical resistance, using polyetheretherketone (PEEK) for the polymer and carbon fibers for reinforcement, with the insert providing additional compressive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metal machining is used to manufacture diaphragm holders, then mechanical strength and compressive resistance are improved, but mass and manufacturing cost increase
Solution Approach 1:
The patent applies composite materials by combining thermoplastic polymer (PEEK) with short carbon fibers to create a fiber-reinforced composite material. This composite provides both the mechanical strength needed for diaphragm holder applications and the weight reduction benefits of polymer materials, resolving the contradiction between strength and mass.
Solution Approach 2:
The manufacturing process is segmented into two distinct phases: first forming the polymer matrix structure, then embedding carbon fibers during a second injection phase. This segmentation allows each material component to be optimized independently for its specific function while achieving the desired balance between strength and weight.
2Weight of moving object
If thermoplastic polymer injection molding is used to reduce mass, then manufacturing time and cost are reduced, but mechanical properties like compressive failure resistance are insufficient
Solution Approach 1:
The patent enhances the thermoplastic polymer with short carbon fibers (length less than 1mm) to create a composite material that maintains the low mass and easy manufacturability of polymers while significantly improving compressive failure resistance and other mechanical properties.
Solution Approach 2:
The patent changes the material parameters by selecting specific polymer types (PEEK with specified tensile strength and elongation properties) and fiber characteristics (carbon fibers with specific length and orientation), optimizing the composite formulation to achieve both low mass and high compressive resistance.
3Device complexity
If simple injection molding is used to manufacture diaphragm holders, then manufacturing complexity is reduced, but complex geometries and variable wall thicknesses cannot be achieved
Solution Approach 1:
The injection molding process is segmented into multiple phases: first injecting the polymer matrix to form the base structure, then injecting carbon fibers to reinforce specific areas. This segmented approach enables complex geometries and variable wall thicknesses that would be difficult to achieve with simple single-phase injection molding.
Solution Approach 2:
The polymer matrix is formed first as a preliminary structure, creating the basic geometry and wall thickness variations. Subsequently, carbon fibers are embedded into this pre-formed structure, allowing the complex final geometry to be achieved through sequential manufacturing steps rather than requiring complex tooling from the outset.
4Strength
If fiber length is increased to improve reinforcement, then mechanical strength improves, but injection molding becomes difficult due to fiber suspension issues
Solution Approach 1:
The patent optimizes the fiber length parameter to be less than 1mm, finding the optimal balance point where sufficient mechanical reinforcement is achieved while the fibers remain short enough to be easily suspended and distributed uniformly during injection molding, avoiding manufacturing difficulties.
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
The method results in a diaphragm holder with improved mechanical resistance and reduced mass, addressing compressive failure and buckling while allowing for complex geometries and reduced material thickness.
Implementation Method 1
This overmolding may in particular be carried out by injection molding
Implementation Method 2
the first material may also comprise fibers, and in particular fibers of a length less than 1 mm, to facilitate their injection in suspension in the thermoplastic polymer in the liquid state. These fibers may for example be made of carbon, a material making it possible to reinforce and substantially stiffen the thermoplastic polymer, while reducing its coefficient of thermal expansion
Implementation Method 3
the insert may be made of a second material, different from the first material, and having a higher compressive strength to density ratio than the first material
Data Source
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AI summary
The invention relates to a method for manufacturing a diaphragm holder (4) for a shock absorber (20) of the oleo-pneumatic type, in particular for an aircraft landing gear (10). The diaphragm holder (4) comprises a first end (101) with a dome (103), and a tubular part (104) extending from the dome (103) to a second end (102). The method comprises a step of overmoulding a first material (M1) onto an insert (200). The insert (200) can be a second material (M2) having a compressive breaking stress value divided by density that is higher than the first material (M1) or, alternatively, made of a material that is identical to the first material (M2). The invention also relates to a diaphragm holder (4) which can be manufactured by this method.