Composite Arm Conical Coupling Glue Stress Reduction
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Solution Overview
Problem
The existing gluing technique for composite material articulated arms in heavy work vehicles results in high shearing forces and significant fatigue damage due to axial forces applied during use, leading to a limited working life of the arm.
Innovation Solution
A conical coupling mechanism is introduced between the box-like structure and joint elements, where the ends are inclined at an angle between 1 and 5 degrees, increasing the overlapping area and reducing tangential stresses on the glue layer, thereby minimizing normal forces and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a traditional gluing technique with parallel ends is used to connect box-like structure and joint element, then the assembly is simple to manufacture, but the shearing force and fatigue damage are high leading to limited working life
Solution Approach 1:
The patent applies asymmetry by changing the symmetric parallel configuration of the box-like structure and joint element ends to an asymmetric conical configuration. The box-like structure has a first end with a conical surface that tapers toward the second end, while the joint element has a corresponding conical surface. This asymmetric conical geometry creates a tapered interference fit that distributes shearing forces more evenly along the glue layer, reducing peak stresses and fatigue damage, thereby extending the working life of the articulated arm while maintaining connection strength.
2Strength
If the overlapping area between box-like structure and joint element is increased, then the stress on glue layer is reduced, but the complexity of the coupling design increases
Solution Approach 1:
The patent applies spheroidality by introducing conical surfaces with curved tapered geometry instead of flat parallel surfaces. The conical surface of the box-like structure and the corresponding conical surface of the joint element create a curved overlapping area when assembled. This curvature naturally increases the surface area of the glue layer while distributing stresses more uniformly. The conical geometry achieves enhanced stress distribution and larger bonding area without requiring complex multi-component couplings, thus balancing strength improvement with manageable design complexity.
Data Source
AI summary
An arm made of composite material, and relative production method, consisting of a plurality of articulated segments with a longitudinal main axis (x), pivoted to each other, each of the articulated segments comprising a box-like structure and at least a joint element attached thereto by means of gluing, the box-like structure having an end cooperating with an end of the joint element on the inside of the surface of the joint element. The ends define a substantially conical reciprocally overlapping area and have profiles concordantly inclined by an angle (α) with respect to the longitudinal axis (x).