Forged Piston Fiber Flow Orientation for Bending Stress Resistance
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Solution Overview
Problem
Conventional forged pistons with radially extending fiber flows face insufficient strength and fatigue endurance when weight reduction is attempted, leading to inadequate bending stress resistance and impact endurance.
Innovation Solution
The method involves working a workpiece made of aluminum, magnesium, or titanium alloys to have fiber flows that are nonparallel to the predetermined forging direction, either radially or slidably, through processes like twisting, to enhance strength and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the piston weight is reduced to improve engine performance, then the piston can achieve better fuel efficiency and dynamic response, but the bending stress resistance becomes insufficient
Solution Approach 1:
The fiber flow orientation is optimized locally in different regions of the piston. In the piston head, fiber flows extend in the radial direction to withstand explosion pressure, while in the piston skirt, fiber flows extend parallel to the sliding direction to resist lateral forces and fatigue, allowing weight reduction without compromising local strength requirements
Solution Approach 2:
The fiber flow directions are predetermined during the forging process to align with the principal stress directions before the piston is put into service. This preliminary orientation of metal flows ensures that the piston structure is pre-configured to resist bending stresses and fatigue loads, enabling weight reduction while maintaining adequate strength
2Weight of moving object
If the piston skirt thickness is reduced to decrease weight, then the engine performance improves, but the fatigue endurance becomes insufficient
Solution Approach 1:
The fiber flow orientation is specifically optimized in the piston skirt region to extend parallel to the sliding direction, providing enhanced resistance against lateral forces and fatigue loads from repetitive impacts, allowing the skirt thickness to be reduced while maintaining fatigue endurance
Solution Approach 2:
The forging process creates curved and continuous fiber flow patterns in the piston skirt that follow the sliding direction, providing smoother stress distribution and enhanced fatigue resistance compared to straight or discontinuous fiber orientations
3Stress or pressure
If the fiber flows extend radially in the piston head, then the explosion pressure resistance is improved, but the bending stress resistance becomes insufficient
Solution Approach 1:
The fiber flow orientation is differentiated between regions: radial extension in the piston head for explosion pressure resistance, and parallel extension along the sliding direction in the piston skirt for bending and fatigue resistance, optimizing performance for each specific loading condition
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 resulting forged piston exhibits increased strength against bending stress and improved fatigue endurance, effectively addressing the limitations of conventional designs by optimizing fiber flow orientations.
Implementation Method 1
forging the workpiece with stress applied thereto in a predetermined direction
Data Source
AI summary
A method of making a forged piston includes the steps of providing a workpiece made of an aluminum alloy, a magnesium alloy or a titanium alloy; and forging the workpiece with stress applied thereto in a predetermined direction (forging direction). The method further includes, before the step of forging, the step of working the workpiece such that fiber flows of the workpiece are nonparallel to the predetermined direction.