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Eliminating Wrinkle and Overlap Defects in AFP Composite Pressure Vessel Manufacturing



Overcoming Wrinkle and Overlap Defects in Automated Fiber Placement for Composite Pressure Vessels

Composite pressure vessels have been widely used for decades in various industries such as aerospace, military, and marine applications due to their lightweight and high-strength properties. However, the automated fiber placement (AFP) process, which is a cutting-edge technology for fabricating composite pressure vessels, faces significant challenges in terms of wrinkle and overlap defects.

Key issues with AFP for composite pressure vessels:

  • Out-of-plane buckling and wrinkling of thermoplastic prepreg tows during steering, especially on dome sections

  • Gaps and overlaps between adjacent prepreg tows, leading to non-uniform thickness and dimensional inaccuracies

  • Reduced mechanical properties and potential damage/failure in areas with defects

  • Lower production efficiency due to increased shearing and re-feeding of prepreg tows

Recent research has focused on addressing these problems through advanced placement path planning algorithms. Some notable approaches include:

  • Optimizing prepreg trajectories considering shell geometry and wrinkle formation mechanisms

  • Developing layup quality evaluation criteria based on prepreg deformability

  • Generating continuous, collision-free placement paths for complex surfaces using computational methods

However, there is still a need for a comprehensive solution that can generate wrinkle-free and defect-free placement paths for the entire pressure vessel structure, including the challenging dome sections. This is critical for improving the quality, performance, and efficiency of AFP-manufactured composite pressure vessels.


Wrinkle and Overlap Defects Impeding Quality and Efficiency in Automated Fiber Placement of Composite Pressure Vessels

The presence of wrinkle and overlap defects in AFP-manufactured composite pressure vessels can have severe consequences on their structural integrity and performance.

Wrinkle defects, caused by out-of-plane buckling of prepreg tows during steering operations, can lead to:

  • Resin-rich areas and voids

  • Reduced load-carrying capacity

  • Potential delamination and failure initiation sites

Overlap defects, resulting from gaps between adjacent prepreg tows, can cause:

  • Non-uniform thickness distribution

  • Dimensional inaccuracies and shape distortions

  • Increased weight and material waste

These defects not only compromise the mechanical properties and reliability of the composite pressure vessel but also hinder the efficiency and productivity of the AFP process. Key pain points include:

  • Increased downtime for manual inspection and repair of defects

  • Higher scrap rates and material consumption

  • Longer production cycles and lower throughput

  • Difficulty in achieving consistent quality, especially for complex geometries like domes

The impact of wrinkle and overlap defects extends beyond the manufacturing process. End-users of composite pressure vessels, such as aerospace and marine industries, face increased risks and costs associated with:

  • Premature failure and reduced service life

  • More frequent maintenance and replacement

  • Potential safety hazards and liability issues

Addressing these defects is paramount for manufacturers to deliver high-quality, reliable, and cost-effective composite pressure vessels. This requires advanced placement path planning solutions that can minimize or eliminate wrinkle and overlap defects while optimizing production efficiency.


Novel Path Planning Approach Integrating Wrinkle-Free Criterion and Defect-Free Algorithms for Ellipsoidal Dome and Cylinder Sections

To address the challenges of wrinkle and overlap defects in AFP of composite pressure vessels, the authors propose a novel path planning approach that integrates a wrinkle-free criterion and defect-free algorithms specifically tailored for the ellipsoidal dome and cylinder sections.

Key features of the approach:

  1. Wrinkle-free placement path equations for ellipsoidal dome section

    1. Derived from wrinkle defect criterion based on prepreg deformation characteristics

    2. Considers shell geometry, geodesic curvature, and minimum steering radius

    3. Enables calculation of wrinkle-free laying angle range and fiber paths

  2. Defect-free placement path planning algorithm for ellipsoidal dome section

    1. Achieves gap-free, overlap-free, and wrinkle-free placement

    2. Determines optimal laydown angles based on prepreg width and dome geometry

    3. Ensures uniform fiber distribution and full coverage

  3. Wrinkle-free placement path equations for cylinder section

    1. Analytically derived based on constant cross-section and zero Gaussian curvature

    2. Provides a theoretical foundation for variable-angle placement without wrinkles

    3. Allows calculation of laying angle range and fiber paths

  4. Full coverage simulation and verification

    1. Models the continuous placement process with multiple circuits and offset

    2. Determines the required number of circuits and mandrel rotation angles

    3. Validates the uniform coverage and defect-free placement paths

The approach leverages advanced computational methods and geometric analysis to generate optimized placement paths that minimize defects and maximize efficiency. Key advantages include:

  • Direct generation of laying angle ranges and fiber paths, reducing trial-and-error

  • Adaptability to different prepreg materials and pressure vessel geometries

  • Compatibility with optimization algorithms for further refinement

  • Potential for integration with AFP machine control systems


Simulated Verification of Wrinkle-Free, Defect-Free, and Full Coverage Placement Paths with Optimized Motion Control Parameters for High-Quality and Efficient Automated Fiber Placement of Composite Pressure Vessels

The proposed path planning approach has been rigorously validated through simulations and experimental verification, demonstrating its effectiveness in generating

high-quality, defect-free placement paths for composite pressure vessels.

Simulation results:

  1. Wrinkle-free placement paths for ellipsoidal dome section

    1. Generated fiber paths within the calculated wrinkle-free laying angle range

    2. Verified reduction of wrinkle formation compared to conventional geodesic paths

  2. Defect-free placement paths for ellipsoidal dome section

    1. Achieved uniform fiber distribution without gaps or overlaps

    2. Demonstrated adaptability to different dome geometries and prepreg widths

  3. Wrinkle-free placement paths for cylinder section

    1. Validated the analytical equations for variable-angle placement

    2. Confirmed the elimination of wrinkle defects in the cylinder region

  4. Full coverage simulation

    1. Verified the complete and uniform coverage of the pressure vessel with optimal number of circuits

    2. Determined the required mandrel rotation angles for seamless transitions

Experimental verification:

  • Implemented the generated placement paths on an AFP machine

  • Analyzed the laid-up prepreg samples for wrinkle, gap, and overlap defects

  • Confirmed the significant reduction of defects compared to conventional paths

  • Validated the improved mechanical properties and dimensional accuracy of the composite pressure vessel

Optimized motion control:

  • Developed algorithms for coordinated motion of the AFP machine's axes

  • Generated control inputs based on the optimized placement paths and laying angles

  • Achieved smooth and precise laying of prepreg tows with minimal vibration and disturbance

  • Demonstrated improved production efficiency and reduced cycle times

The simulation and experimental results confirm the effectiveness of the proposed approach in delivering wrinkle-free, defect-free, and full coverage placement paths for composite pressure vessels. The optimized motion control ensures the reliable and efficient execution of these paths on AFP machines.

Key benefits:

  • Improved structural integrity and performance of composite pressure vessels

  • Reduced scrap rates, material waste, and manual rework

  • Increased production throughput and cost-effectiveness

  • Potential for automation and industrial implementation



We would like to express my sincere gratitude to the authors Bo Wang, Lihua Wen, Jinyou Xiao, Shiyu Wang, Ping Ren, Liqiang Wang, Lei Zu, and Xiao Hou for their valuable contributions in writing this blog post. Their research paper, "Automated Fiber Placement Path Planning and Analysis of Pressure Vessels," served as the foundation for the content presented here.

Their innovative approach to optimizing automated fiber placement for composite pressure vessels, which integrates wrinkle-free criteria and defect-free algorithms, has the potential to revolutionize the manufacturing process. The comprehensive simulations and experimental validations conducted by the authors demonstrate the effectiveness of their method in reducing defects, improving quality, and increasing efficiency.


What's Next!

Discover the future of composite manufacturing with Addcomposites! Here's how you can get involved:

  1. Stay Informed: Subscribe to our newsletter to receive the latest updates, news, and developments in AFP systems and services. Knowledge is power, and by staying informed, you'll always have the upper hand. Subscribe Now

  2. Experience Our Technology: Try our cutting-edge simulation software for a firsthand experience of the versatility and capability of our AFP systems. You'll see how our technology can transform your production line. Try Simulation 

  3. Join the Collaboration: Engage with us and other technical centers across various industries. By joining this collaborative platform, you'll get to share ideas, innovate, and influence the future of AFP. Join Collaboration 

  4. Get Hands-On: Avail our educational rentals for university projects or semester-long programs. Experience how our AFP systems bring about a revolution in composite manufacturing and leverage this opportunity for academic and research pursuits. Request for Educational Rental

  5. Take the Next Step: Request a quotation for our AFP systems. Whether you're interested in the AFP-XS, AFP-X, or SCF3D, we are committed to offering cost-effective solutions tailored to your needs. Take the plunge and prepare your production line for the next generation of composite manufacturing. Request Quotation

At Addcomposites, we are dedicated to revolutionizing composite manufacturing. Our AFP systems and comprehensive support services are waiting for you to harness. So, don't wait – get started on your journey to the future of manufacturing today!


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