Concave Ram Body Socket Geometry for Fretting Corrosion Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The stiff contact between CRES ram bodies and spherical bearings in primary flight controls leads to fretting corrosion and subsequent fatigue, which existing designs fail to adequately address, despite regulations requiring reduced Cadmium levels.
Innovation Solution
A modified ram body design with concave sections on its inner surface, matching the shape and size of the spherical bearing, reduces fretting corrosion by distributing stress and eliminating the need for interface products like silver plating, thereby enhancing the structural integrity and reducing material weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CRES ram bodies and spherical bearings are used with stiff contact, then structural strength and load-bearing capacity are improved, but fretting corrosion and fatigue occur at contact points
Solution Approach 1:
The patent applies different surface treatments to specific contact zones of the spherical bearing. The equatorial region receives a copper-based coating while the polar regions maintain the original CRES surface or receive different treatment, creating localized property variations that prevent fretting corrosion at high-stress contact points while maintaining overall structural strength
Solution Approach 2:
The patent uses composite material structures by combining CRES base material with copper-based surface coatings. This creates a multi-layer composite structure where the CRES provides structural strength and the copper-based coating provides corrosion resistance at contact surfaces, effectively addressing both strength and reliability requirements
2Reliability
If interface products like silver plating are applied to prevent fretting corrosion, then corrosion resistance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the material composition parameter of the surface coating from traditional silver plating to copper-based materials. This parameter change maintains corrosion prevention functionality while simplifying the manufacturing process and reducing costs, as copper-based coatings can be applied more easily and are more compatible with CRES substrates
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A ram-body (100) for use with a spherical bearing (700) is described herein, the ram body (100) having an inner circumferential surface (101). The ram body (100) comprises at least a first concave section (102) provided in said inner circumferential surface (101). In some examples, a second concave section (103) may be provided diametrically opposite to the first concave section (102). In some examples, the concave sections (102, 103) may be lunular shaped. A method of manufacturing the ram body (100) is also described. A ram body and spherical bearing assembly is also described.