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Narrow UD tapes to bridge the ATL-AFP gap

It is well understood that automated tape laying (ATL) and automated fiber placement (AFP) were the enabling technologies in the application of carbon fiber composites in major aerostructures for the Boeing 787 and the Airbus A350 aircraft. Prior to the development of these planes, composites had been applied in gradually increasing amounts in commercial aircraft for more than 30 years, but mainly in secondary structures using hand layup and some automated manufacturing processes.

With the 787 and the A350, however, Boeing (Seattle, Wash., U.S.) and Airbus (Toulouse, France) responded to demand for lighter weight aircraft, which accelerated adoption of composite materials and processes for use in fuselage skins, stringers, frames, wing skins, wing spars, wing boxes and tail structures. ATL and AFP led the charge, allowing each OEM, and their suppliers, to efficiently lay down large amounts of prepregged UD-tape and tows.

ATL found a place fabricating wing structures, which, being modestly contoured, took advantage of the wide format (3, 6 or 12 inches) of the tape products, which could be laid down quickly. However, what ATL offered in speed and volume it sacrificed in conformability.

AFP, on the other hand, which lays down multiple tows 0.125 to 0.5 inch wide, found a place fabricating fuselage and other more contoured structures that demand maximum flexibility and conformability. However, what ATL offered in conformability it sacrificed in speed and volume.

Further, as enabling as these technologies were, they clearly reflected the state of ATL/AFP art at the time of the planes’ initial development, almost 20 years ago now. Indeed, the production pace of the 787 and the A350 (each now less than 10/month in light of the coronavirus pandemic) is well-aligned with previous-generation ATL/AFP technologies, which are relatively slow. These technologies also depend on human operators to provide in-process visual inspection and quality control, checking for the laps, gaps, wrinkles, foreign object debris (FOD) and other flaws endemic to the automated laydown process. This quality control step represents a significant bottleneck in the manufacture of composite structures.

But as commercial aircraft manufacturers look to the future (well beyond the coronavirus pandemic) and the aircraft they will develop — particularly new single-aisle (NSA) programs to replace the Boeing 737 and Airbus A320 — shipset volumes are likely to be on the order of 60-100 per month. This demands composite materials and process capability orders of a magnitude more efficient than those used to fabricate structures for the 787 and the A350.

Honeycomb panel applications

EconCore has granted plastic film company Renolit a license for the continuous production of honeycomb panel.

Renolit has reportedly used the honeycomb in its Gorcell range of products for automotive, outdoor kitchens, truck superstructures, and bakery panels applications. More recently, Renolit has produced products for gardens, balconies and terraces made with honeycomb panels.

According to EconCore, the honeycomb has helped Renolit improve panel planarity, reduce golf ball effect, and create smooth, scratch free surfaces.

The Renolit Gorcell production process includes film unwinding, vacuum forming, core calibration, skin layer lamination, panel calibration and cutting.

This story uses material from EconCore, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.

Scanning electron microscopy and digital image correlation observations reveal the failure mechanisms of overmolded hybrid composites. The failure behavior of overmolded hybrid composites is mainly CFRT laminates failure for all cases. The evolution of non-uniform strain fields indicates that the fracture of overmolded thermoplastic composites may initiate at the edges and spread out to the far fields.

INTRODUCTION

Wood is a renewable, ecological raw material employed to manufacture high quality furniture and everyday products. Its versatile utilization in numerous branches of the wood industry exerts considerable influence on the intensive exploitation of wood resources. The above-mentioned factors clearly show that there are reasons to replace traditional panel materials, such as plywood (PW), particleboard (PB), oriented strand board (OSB), medium-density fiberboard (MDF), and high-density fiberboard (HDF), with lightweight sandwich honeycomb panels. These panels are characterized by relatively high strength and stiffness (Khan 2006; Schwingshackl et al. 2006; Jen and Chang 2008; Smardzewski 2013). According to Negro et al.(2011), the density of light honeycomb panels should not exceed 500 kg/m3.

The use of honeycomb panels with paper cores manufactured from hexagonal cells is quite widespread. However, during the manufacturing process these cells acquire irregular shapes of non-regular hexagons (Xu et al. 2008). In a study conducted by Smardzewski and Prekrat (2012) it was demonstrated that the core of a honeycomb panel made of irregular hexagonal cells placed between two HDF panels equalizes quite well the stresses that develop in the facings. The above researchers observed that the stiffness and strength of the honeycomb panels were affected significantly by the paper grammage as well as the cell shapes and dimensions.

Honeycomb structures find widespread application in the motor, airplane, and military industries (Schmueser and Wickliffe 1987). In the furniture industry, due to economic reasons, honeycomb panels with thicknesses exceeding 25 mm (Barboutis and Vassiliou 2005; Smardzewski 2015; Smardzewski and Jasińska 2016) are preferred. Furthermore, physico-chemical properties of honeycomb panels with hexagonal cells manufactured from light metals are commonly known (Paik et al. 1999; Schwingshackl et al. 2006; Said and Tan 2008).

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