Composite Material Joining After Thermal Expansion Pre-Machining
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Solution Overview
Problem
The production of composite materials from materials with different coefficients of thermal expansion often results in thermal stresses and cracking due to the formation of tensile stresses, particularly in the material with the lower coefficient of expansion, and existing methods like introducing a nickel layer between materials do not adequately prevent these stresses.
Innovation Solution
A method involving heating the material with the higher coefficient of thermal expansion to its maximum temperature, machining it to the desired geometry, and then connecting it directly with another material without additional intermediates, ensuring no further volume increase and thus preventing tensile stresses, using techniques like cold gas spraying for precise geometry and stable bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If materials with different coefficients of thermal expansion are joined using conventional methods, then the composite material can be produced, but thermal stresses and cracking occur during heating
Solution Approach 1:
The first material is pre-heated to the maximum process temperature and machined to the desired geometry before joining with the second material. This preliminary thermal expansion and machining ensures that no further volume increase occurs during subsequent heating, preventing tensile stress development in the composite material during the joining process
Solution Approach 2:
The invention changes the temperature parameter dynamically: the first material is heated to maximum temperature for machining, then cooled to room temperature for joining, and finally reheated to the maximum temperature. This parameter change sequence ensures that thermal expansion occurs before joining, eliminating tensile stresses during heating after assembly
2Ease of manufacture
If a nickel layer is applied between steel and copper to join them, then bonding between the dissimilar materials is achieved, but additional material is required and thermal stresses are not adequately prevented
Solution Approach 1:
The invention removes the intermediate nickel bonding layer from the joining process. By pre-heating and machining the first material to its final geometry before joining, the patent achieves direct bonding between dissimilar materials without requiring any intermediate material, thereby simplifying the composite structure while preventing thermal stresses
Solution Approach 2:
The first material undergoes preliminary heating and machining to the desired geometry before the actual joining process. This preliminary action ensures that the material is already at its final dimensions and shape, eliminating the need for intermediate bonding materials and preventing thermal stress during the joining operation
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 method effectively prevents cracking in the composite material by controlling thermal expansion and ensuring a stable connection between materials with different coefficients of expansion, resulting in a permanently stable composite with reduced tensile stress.
Implementation Method 1
the first material is heated to a temperature corresponding to the maximum temperature to be applied in the entire process, during which it expands in volume
Implementation Method 2
dynamic cold gas spraying of the contoured surface to form superimposed butt-welded metal particle layers
Data Source
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AI summary
The invention relates to a method for producing a composite material from at least one first material (2) and a second material (1), wherein the first material (2) has a higher coefficient of thermal expansion than the second material (1). The method comprises the steps of: heating the first material (2) with volume expansion of the first material (2) to a temperature corresponding to the maximum temperature to be applied in the method, machining the first material (2) to the desired component geometry, and joining the second material (1) to the first material (2).