Multi-layer Piezoelectric Element Crack Propagation Control
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Solution Overview
Problem
Multi-layer piezoelectric elements face challenges in maintaining stability and preventing short-circuiting under high voltage and pressure conditions due to unpredictable crack growth in target fracture layers, leading to reduced displacement and durability.
Innovation Solution
Incorporating a low-rigidity metal or ceramic layer with separated metal or ceramic parts that are bonded with only one piezoelectric material layer, allowing stress dispersion and preventing crack propagation into the piezoelectric material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a target fracture layer is provided in the piezoelectric material layer to relieve stress, then stress relief is achieved to some extent, but cracks may grow in unpredictable directions and propagate into the piezoelectric material layer under high voltage conditions
Solution Approach 1:
The target fracture layer is segmented into a plurality of regions, with each region containing multiple through-holes. This segmentation allows cracks to be contained within individual regions and prevents unpredictable crack propagation into the piezoelectric material layer, while still maintaining the stress relief function.
Solution Approach 2:
The target fracture layer has different local structures: regions with through-holes for crack containment and regions without through-holes for stress relief. This local quality variation allows the layer to simultaneously achieve stress relief and crack growth control in different areas.
2Length of moving object
If the multi-layer piezoelectric element is operated under higher voltage for greater displacement, then displacement capability is improved, but stress intensity increases causing unpredictable crack growth
Solution Approach 1:
The target fracture layer with through-holes is designed in advance to cushion and contain crack growth before it can propagate into the piezoelectric material layer. This beforehand cushioning allows the element to operate under higher voltage for greater displacement while preventing catastrophic failure from stress-induced cracks.
3Ease of manufacture
If the target fracture layer and piezoelectric material layer are formed from the same material, then manufacturing is simplified, but cracks generated in the target fracture layer can grow into the piezoelectric material layer
Solution Approach 1:
The target fracture layer is segmented into multiple regions with through-holes that act as crack barriers. This segmentation maintains the benefit of using the same material for both layers (ease of manufacture) while preventing crack propagation into the piezoelectric material layer through the physical barriers created by the through-holes.
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 solution effectively suppresses displacement variation and enhances durability by absorbing stress in the low-rigidity layer, preventing short-circuiting and maintaining reliable operation under continuous high-voltage and high-pressure conditions.
Implementation Method 1
Incorporating a low-rigidity metal or ceramic layer with separated metal or ceramic parts that are bonded with only one piezoelectric material layer, allowing stress dispersion and preventing crack propagation into the piezoelectric material layers
Implementation Method 2
Multi-layer piezoelectric element, and ejection apparatus and fuel ejection system that employ the same... a multi-layer structure in which a plurality of piezoelectric material layers and a plurality of metal layers are stacked alternately one on another
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The application refers to a multi-layer piezoelectric element (1) comprising a multi-layer structure (7) in which a plurality of ceramic layers (21) and a plurality of internal electrodes (11) are stacked alternately one on another, wherein the plurality of ceramic layers (21) comprise piezoelectric material layers (3) and low-rigidity ceramic layer (23) that has rigidity lower than those of the piezoelectric material layer (3) and the internal electrode (11), wherein the low-rigidity ceramic layer (23) comprises a plurality of ceramic parts (25) that are separated from each other, and wherein at least one of the ceramic parts (25) is bonded with only one piezoelectric material layer (3) among the two piezoelectric material layers (3) that adjoin in the stacking direction.