Laser Perforation of Acoustic Panel Skins With Dual Pulse Width Beams
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Solution Overview
Problem
Existing laser perforation systems face challenges in forming holes in acoustic panel skins, particularly in fiber-reinforced plastics, due to differences in thermal properties between the fiber-reinforcing material and the polymer matrix, leading to heat-affected zones that affect structural integrity and airflow efficiency.
Innovation Solution
A laser perforating system that uses a combination of short pulse width (SPW) and long pulse width (LPW) beams, with the SPW beam ablating the perimeter portion and the LPW beam ablating the center portion, to minimize heat-affected zones and achieve a smoother, more uniform hole formation, while adjusting laser power based on radial distance from the axial centerline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single laser beam with uniform pulse width is used for perforation, then the processing speed is maintained, but heat-affected zones increase and structural integrity deteriorates
Solution Approach 1:
The laser beam is segmented into two distinct pulse width components: a short pulse width beam (5-50 nanoseconds) for perimeter ablation and a long pulse width beam (50-500 nanoseconds) for center ablation. This segmentation allows different regions of the hole to be processed with optimized parameters, reducing heat-affected zones while maintaining processing efficiency.
Solution Approach 2:
Different pulse width parameters are applied to different spatial locations within the hole perimeter. The short pulse width beam targets the perimeter region where structural integrity is critical, while the long pulse width beam targets the center region where material removal efficiency is prioritized. This local quality differentiation resolves the contradiction between speed and strength.
2Productivity
If high laser power is applied to ablate material quickly, then productivity increases, but heat-affected zones expand and damage surrounding material
Solution Approach 1:
The laser processing employs periodic pulsed action with two distinct pulse width regimes. Short pulses deliver high peak power for precise perimeter ablation with minimal heat diffusion, while long pulses provide sustained energy for efficient center material removal. The periodic alternation between these pulse modes enables high productivity while controlling heat-affected zones through temporal separation of high-power and sustained-power phases.
3Ease of operation
If laser power is uniformly distributed across the hole perimeter, then the process is simple to control, but hole diameter consistency deteriorates due to radial temperature gradients
Solution Approach 1:
The laser power distribution is made asymmetric with respect to radial position: higher power density is applied at the perimeter through short pulses, while lower power density is applied at the center through long pulses. This asymmetric power distribution compensates for radial temperature gradients that would otherwise cause hole diameter variations, achieving consistent hole dimensions while maintaining relatively simple process control through automated parameter switching.
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 approach reduces the severity of heat-affected zones, resulting in holes with consistent diameters and improved structural characteristics, enhancing airflow efficiency and reducing damage to surrounding material.
Implementation Method 1
generating a short pulse width (SPW) beam with the at least one laser source and directing the SPW beam to the skin at a hole location
Implementation Method 2
to ablate a first portion of a skin material at the hole location
Data Source
AI summary
A laser perforating system includes at least one laser source and a controller. The controller includes a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to control the at least one laser source to form a hole in a skin by: generating a short pulse width (SPW) beam with the at least one laser source and directing the SPW beam to the skin at a hole location for the hole and generating a long pulse width (LPW) beam with the at least one laser source and directing the LPW beam to the skin at the hole location.