The experimental determination of prepreg tack and dynamic stiffness

Crossley, Richard; Schubel, Peter; Warrior, N.A.

doi:10.1016/j.compositesa.2011.10.014

Cited by 61 publications

(58 citation statements)

References 12 publications

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“…However the tack response to changes in temperature is dependent on the type of material. Findings reported by Crossley et al [16] show that some prepreg materials experience increased tack with increased temperature while others show reduced tack when the temperature is increased.…”

Section: Prepreg Handling and Gripper Technologiesmentioning

confidence: 91%

Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry

Björnsson¹,

Lindbäck²,

Eklund³

et al. 2015

SAE Int. J. Mater. Manf.

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With an increased use of composite materials within the aerospace industry follows a need for rational and cost-effective methods for composite manufacturing. Manual operations are still common for low to medium manufacturing volumes and complex products. Manual operations can for example be found in material handling, when picking prepreg plies from a cutter table and stacking them to form a plane laminate in preparation for a subsequent forming operation. Stacking operations of this kind often involves a great number of different ply geometries and removal of backing paper and other protecting materials like plastic. In this paper two different demonstrator cells for automated picking of prepreg plies and stacking of plane laminates are presented. One demonstrator is utilizing a standard industrial robot and an advanced end-effector to handle the ply variants. The other demonstrator is using a dual arm robot which allow for simpler end-effector design. In combination with a previously developed system for automated removal of backing papers both systems have shown to be capable of automatically picking prepreg plies from a plane surface and stack them to generate a flat multistack laminate. The dual arm approach has shown advantageous since it result in simpler end-effector design and a successive lay down sequence that result in good adhesion between the plies in the laminate.

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Section: Prepreg Handling and Gripper Technologiesmentioning

confidence: 91%

Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry

Björnsson¹,

Lindbäck²,

Eklund³

et al. 2015

SAE Int. J. Mater. Manf.

View full text Add to dashboard Cite

show abstract

“…The tack level can be altered by varying any of the four variables [3]. For material used for manual layup the level of tack is relatively flexible, since the operator's flexibility can compensate for tack variations [4]. In automated manufacturing solutions the need to control the tack level increases [4].…”

Section: Prepreg Materials and Its Propertiesmentioning

confidence: 99%

“…For material used for manual layup the level of tack is relatively flexible, since the operator's flexibility can compensate for tack variations [4]. In automated manufacturing solutions the need to control the tack level increases [4]. In both automatic and manual layup of composite material the layup of the first layer is considered to be the most difficult, since the tool often has a smooth surface that, in some cases, is treated with release agents.…”

Section: Prepreg Materials and Its Propertiesmentioning

confidence: 99%

“…Adding heat, however, does not always increase the level of tack. In experiments with three different materials, Crossley et al [4] show that the three materials' levels of tack respond quite differently to an increased temperature. Another way to increase the level of tack, and thereby increase the layup reliability, is to treat the mold surface with a tackifier.…”

Section: Prepreg Materials and Its Propertiesmentioning

confidence: 99%

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Automated Removal of Prepreg Backing Paper - A Sticky Problem

Björnsson¹,

Lindbäck²,

Johansen³

2013

SAE Technical Paper Series

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Automated solutions for manufacturing composite products based on prepreg often imply Automatic Fiber Placement or Automatic Tape Laying. These systems are generally associated with huge investments. For certain manufacturing applications it is interesting to investigate alternatives to find simpler and less costly automation. One example of an automated system could be the use of a standard industrial robot to pick single prepreg plies from an automated cutting machine and stack them to form a plane laminate. This paper is based on a case illustrating a product from the aircraft manufacturing industry. The case will demonstrate a pick and place concept on a general level and illustrate challenges that must be solved. The challenge selected to be the main focus for this paper is an automated process for backing paper removal. A literature review of different gripping technologies reveals several interesting technologies, and the most promising are tested for backing paper removal. The tests show that an automated removal process can be designed by using standard vacuum grippers in combination with mechanical clamping grippers. In order to lift the backing paper with a vacuum gripper an initial separation between the backing paper and prepreg is needed. This separation is most easily mechanically induced by bending the material. The proposed solution for automatic backing paper removal can be integrated in a manufacturing cell for manufacturing of the studied product.

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“…The dependencies between tack and other parameters is complex. It has been shown that the material age can affect the tack response to heating [65], and that different prepreg materials exhibit very different responses to temperature changes, where low-tack prepreg shows an increased tack and high tack prepreg shows a decreased tack with increased temperatures [66]. The bond between two pieces of prepreg or a piece of prepreg and another surface is also affected by the contact time and force used during attachment [64].…”

Section: Prepregmentioning

confidence: 99%

Automated layup and forming of prepreg laminates

Björnsson¹

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Composite materials like carbon fiber-reinforced polymers (CFRPs) present highly appealing material properties, as they can combine high strength with low weight. In aerospace applications, these properties help to realize lightweight designs that can reduce fuel consumption. Within the aerospace industry, the use of these types of materials has increased drastically with the introduction of a new generation of commercial aircraft. This increased use of CFRP drives a need to develop more rational manufacturing methods.For aerospace applications, CFRP products are commonly manufactured from a material called prepreg, which consists of carbon fibers impregnated with uncured polymer resin. There are two dominant manufacturing technologies for automated manufacturing using prepreg, automated tape layup and automated fiber placement. These two technologies are not suitable for all types of products, either due to technical limitations or a combination of high investment costs and low productivity. Automation alternatives to the two dominant technologies have been attempted, but have so far had limited impact. Due to the lack of automation alternatives, manual manufacturing methods are commonly employed for the manufacturing of complex-shaped products in low to medium manufacturing volumes.The research presented in this thesis aims to explore how automated manufacturing systems for the manufacturing of complex CFRP products made from prepreg can be designed so that they meet the needs and requirements of the aerospace industry, and are suitable for low to medium production volumes. In order to explore the area, a demonstrator-centered research approach has been employed. A number of demonstrators, in the form of automated manufacturing cells, have been designed and tested with industrial and research partners. The demonstrators have been used to identify key methods and technologies that enable this type of manufacturing, and to analyze some of these methods and technologies in detail. The demonstrators have also been used to map challenges that affect the development of enabling methods and technologies.Automated manufacturing of products with complex shapes can be simplified by dividing the process into two steps. Thin layers of prepreg are laid up on top of each other to form flat laminates that are formed to the desired shape in subsequent forming operations. The key methods and technologies required to automate such a system are methods and technologies for automated prepreg layup, the automated removal of backing paper and the forming of complex shapes. The main challenges are the low structural rigidity and tacky nature of prepreg materials, the extensive quality requirements in the aerospace industry and the need for the systems to handle a wide array of prepreg shapes.The demonstrators show that it is possible to automate the manufacturing of complexshaped products using automated layup and forming of prepreg laminates. Tests using the demonstrators indicate that it is possible to meet the quality req...

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The experimental determination of prepreg tack and dynamic stiffness

Cited by 61 publications

References 12 publications

Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry

Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry

Automated Removal of Prepreg Backing Paper - A Sticky Problem

Automated layup and forming of prepreg laminates

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