Piezoelectric Actuator Low Elastic Modulus Region Crack Resistance
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Solution Overview
Problem
Piezoelectric actuators experience a reduction in vibration amplitude due to cracks caused by tensile stress, leading to deterioration in their characteristics, as the isolated regions surrounded by cracks result in reduced strain and ineffective driving voltage application.
Innovation Solution
The actuator design includes a main plate with a low elastic modulus region positioned away from the center and peripheral edge, where the piezoelectric element is placed, allowing for increased tensile stress in the deformation control region and reducing the likelihood of isolated regions forming even if cracks occur, thus maintaining vibration amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the piezoelectric element is positioned at the center of the main plate, then the driving voltage is applied uniformly, but tensile stress concentrates at the center causing cracks to form and connect, creating isolated regions that reduce vibration amplitude
Solution Approach 1:
The patent introduces a low elastic modulus region (thinner portion) at a specific position on the main plate where the piezoelectric element is disposed. This local structural modification changes the stress distribution characteristics, causing tensile stress to concentrate in the thinner portion rather than at the center, thereby preventing crack formation and connection while maintaining uniform driving voltage application
2Ease of manufacture
If the main plate has uniform thickness, then the structure is simple to manufacture, but tensile stress concentrates at the center during vibration causing crack connectivity and reduced vibration amplitude
Solution Approach 1:
The patent modifies the main plate structure by creating a local thinner portion (low elastic modulus region) at the position where the piezoelectric element is disposed. This local thickness variation redirects tensile stress to the thinner portion during vibration, preventing stress concentration at the center and subsequent crack formation, while maintaining overall manufacturing feasibility
Solution Approach 2:
The patent changes the elastic modulus parameter of the main plate by creating a thinner portion with reduced thickness. This parameter modification alters the stress distribution pattern during vibration, causing tensile stress to concentrate in the thinner portion rather than at the center, thereby improving crack resistance while maintaining structural integrity
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 configuration effectively suppresses the reduction in vibration amplitude and improves the actuator's vibration characteristics by distributing tensile stress away from the center, reducing crack connectivity and maintaining efficient driving voltage application.
Implementation Method 1
a piezoelectric element 30, vibrates a flat plate
Implementation Method 2
The main plate includes a low elastic modulus region that, as viewed in plan, overlaps the piezoelectric element and that does not include the peripheral edge nor a rotation center of the main plate. The low elastic modulus region has an elastic modulus smaller than that of a central region of the main plate positioned in the vicinity of the rotation center.
Data Source
AI summary
An actuator includes a main plate, a frame, a connection member, and a piezoelectric element. The main plate has a principal surface and a principal surface and has a rotationally symmetrical shape as viewed in plan. The frame is disposed at a position outside a peripheral edge of the main plate. The connection member is connected to the peripheral edge of the main plate and to the frame. The connection member holds the main plate so as to enable the main plate to vibrate relative to the frame. The piezoelectric element is disposed on the principal surface of the main plate, and the circumferential shape of the piezoelectric element is smaller than the main plate. The main plate includes a recess and a thin portion in a region that includes a center and a peripheral edge of the main plate and that overlaps the piezoelectric element as viewed in plan.