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Perforated Composite Applications, Modelling and Manufacture

Back to Core Research Programme 34236-2023-literature-review-on-the-potential-use-of-non-destructive-testing-techniques-for-residual-stress-measurement 34241-2023-artificial-intelligence-for-ndt-scanning-of-unknown-geometries-using-collaborative-robots 34459-2022-friction-stir-welding-of-pressure-vessel-liners-for-the-storage-and-transportation-of-hydrogen 34727-2023-techniques-for-high-temperature-ultrasonic-inspection-of-arc-welding-state-of-the-art-review 34793-2023-update-on-literature-reviews-for-wire-fed-additive-manufacturing 34847-2023-Literature-review-on-crack-length-measurement-techniques-on-environmental-fracture-toughness-tests 35268-2024-Literature-review-on-dual-sensing-applications-for-SHM-of-pipelines 32221-2020-hybrid-composite-to-metal-joining 32893-2020-mechanical-fastener-coatings-for-corrosion-protection 33557-2020-extreme-high-speed-laser-application-ehla-coatings 33557-2020-extreme-high-speed-laser-application-ehla-coatings 33557-2020-extreme-high-speed-laser-application-ehla-coatings 33557-2020-review-of-electric-vehicle-battery-joining-methods-and-testing 34250-2022-thermoplastic-materials-compatibility-for-hydrogen-service A Review of High Power, In-Vacuum and Narrow Gap Laser Welding Processes for Thick Section Welding A Review of High Productivity Additive Manufacture Using a Hybrid Laser-Arc Deposition (HLAD) Process A Review of Micro Welding with Fibre and Disc Continuous-Wave Laser Sources A Review of Residual Stress Measurement Techniques Used for Components Produced Using the Selective Laser Melting Process A Review of the Machine GTAW Ambient Temperature Temper Bead Repair Technique for Nuclear Power Plant Components A Review of Weld Repairs of Mar-M247 and Similar Alloys Applications, Modelling and Manufacturing Processes for Perforated Composites - Literature Review Butt Fusion Welding Procedures and Test Methods Used for PE Pipes Duplex Stainless Steel Welding – A Review of Current Practices Elastic Follow-Up in the Context of Fracture Assessment Flaw Sizing Techniques Using Guided Waves Flaw Sizing Techniques Using Guided Waves Flaw Sizing Techniques Using Guided Waves In-Bore Multi-Positional Laser Welding In-Process Monitoring of Arc Welding for Quality and Defect Detection Mechanical Fastening Technologies for Steel to Aluminium Joining in Automotive Manufacture Process Capability Study for Friction Stir Spot Welding (FSSW) Resistance Spot Welding with Transition Discs – A Review of Dissimilar Joining Using Transition Materials with Specific Reference to Resistance Spot Welding Review of Process Simulations for Metal Additive Manufacturing Surface Modification and Micro-Machining with Pulsed-Laser Sources Wire Fed Electron Beam Additive Manufacture – A State-of-the-Art Review
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TWI Technical Literature Review 25265

By Chris Worrall


There is a clear industrial need for development of perforated materials. Perforated metal sheets are used across many industries for a number of applications including blast protection, acoustic damping, aerodynamic tailoring and aircraft anti-icing. Homogeneous metals are relatively easy to machine into these perforated sheets by milling many holes by laser, waterjet, punching or conventional drilling.

Composite materials can offer significant specific property advantages over metals; high stiffness and strength combined with low weight. Their use as perforated panels, however, is yet to be applied in many applications. There are significant difficulties with machining composite materials; the cost of tools to cut the abrasive fibres, and reduction in structural efficiency when fibres are cut. Even with the best quality tools, abrasion quickly becomes a significant problem when drilling large numbers of holes and the tolerances of the holes diminishes, which introduces variability and damage into the parts. Using state-of-the-art machining techniques, such as laser or abrasive waterjet cutting, can reduce the machining problems. Waterjet cutting of composites, however, will require a small initial pilot hole to be drilled in order to eliminate damage, and this is not economical for many small holes (perforations). For those techniques without this issue there is still the inherent problem that fibres are cut and removed from the composite when making the holes. A greater proportion of the fibres will be cut if a perforated composite is manufactured using this technique, which can significantly reduce the panel’s mechanical properties, and as a result additional material must be added, reducing the potential weight savings expected from using the composite.

Cutting a hole in any material reduces its strength, and composites are no exception. A typical carbon fibre composite can suffer tensile strength reduction of up to 35% through inclusion of a single drilled hole (Poon, 1991), although this figure can depend on the composite lay-up. To address this, a recently completed TWI Core Research Project (CRP) successfully developed a new TWI capability to make holes in thermoplastic composites using a novel Thermally-Assisted Piercing (TAP) technique (Brown and Worrall, 2015). The technique offers a process where holes can be machined in thermoplastic composites with reduced detriment to the load bearing fibres (when compared with current machining techniques). Coupons containing holes made using the TAP process exhibited an improvement in openhole tensile strength of up to 10% compared to coupons with holes made using a conventional drilling/reaming process. Although originally developed as a precursor to mechanical fastening, it became apparent during the project that wider exploitation opportunities were possible; any application that requires holes to be made in composites. The technique is likely to become more attractive economically when the hole size reduces and the number of holes increased (perforation) as this is increasingly difficult to achieve in a fast, cost-effective way with conventional machining techniques. 

This literature review examines several current and potential applications where perforated composites could be exploited to offer improved performance over similar metal-based structures; anti-icing, sound attenuation, blast protection and joining. Materials of interest are both thermoplastic and thermoset composites; thermoplastics for their potential to be perforated after manufacture, and thermosets for the ease of fibre displacement during perforation before the matrix resin has fully cured. The review also covers simulation of both the process of perforating the composite and the performance of the perforated structure. Finally, a review of competing perforating technologies is included to offer insight into when the Thermally-Assisted Piercing process is most likely to be adopted as a perforating technique for composite structures.

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