Possibilities of predicting the strength and stiffness of layered, orthogonally reinforced plastics in interlaminar shear

1976 ◽  
Vol 11 (3) ◽  
pp. 488-490 ◽  
Author(s):  
A. V. Sandalov ◽  
M. Z. Medvedev ◽  
V. F. Zinchenko ◽  
S. N. Belova
Keyword(s):  
Reinforced Plastics ◽  
Interlaminar Shear ◽  
Strength And Stiffness

Applications of Variable-Axial Fibre Designs in Lightweight Fibre Reinforced Polymers

2015 ◽  
Vol 825-826 ◽  
pp. 757-762 ◽  
Author(s):  
Emanuel Richter ◽  
Axel Spickenheuer ◽  
Lars Bittrich ◽  
Kai Uhlig ◽  
Gert Heinrich
Keyword(s):  
Carbon Fibre ◽  
Design Strategies ◽  
Special Design ◽  
Reinforced Polymers ◽  
Reinforced Plastics ◽  
Strength And Stiffness ◽  
Carbon Fibre Reinforced Plastics

A load dependent and curvilinear respectively variable-axial fibre design can notably enhance the strength and stiffness of lightweight components compared to fibre reinforced structures made of common multiaxial fibre textiles. At the Leibniz-Institut für Polymerforschung Dresden e. V. (IPF) special design strategies are in the focus of current studies. Two currently developed components made of carbon fibre reinforced plastics, a lightweight three-legged stool and a lightweight recurve bow riser, are described within this paper.

Intralaminar Reinforcement for Biomimetic Toughening of Bismaleimide Composites Using Nanostructured Materials

Materials ◽  
2005 ◽  
Author(s):  
Thomas Tiano ◽  
Margaret Roylance ◽  
Benjamin Harrison ◽  
Richard Czerw
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Laminated Composite ◽  
High Strength ◽  
Interlaminar Shear Strength ◽  
Aircraft Wings ◽  
Trailing Edges ◽  
Interlaminar Shear ◽  
Strength And Stiffness ◽  
Walled Carbon Nanotubes

Many conventional composite materials are composed of multiple layers of continuous fiber reinforced resin produced by lamination of b-staged prepreg and subsequent cure. These materials exhibit very high strength and stiffness in the plane, dominated by the properties of the fibers. The Achilles heel of such composites is the interlaminar strength, which is dependent on the strength of the unreinforced resin, often leading to failure by delamination under load. Current methods for increasing the interlaminar shear strength of composites consist of inserting translaminar reinforcement fibers through the entire thickness of a laminated composite, such as z-pin technology developed by Foster-Miller [1]. While effective, this technique adds several processing steps, including ultrasonic insertion of the z-pins into the laminate, subsequently causing a significant cost increase to laminated composites. Described in this paper is a process utilizing single-walled carbon nanotubes (SWNTs) and vapor grown carbon nanofibers as reinforcing elements promoting interlaminar shear strength and toughness in carbon fiber/bismaleimide (BMI) resin composites. The resulting composites mimic the natural reinforcing mechanism utilized in insect cuticles. Three different methods of increasing the affinity of these carbon nanofillers for the BMI matrix were explored. The mechanical properties of these composites were assessed using end notch flexure testing. The results indicated that including nanofiller at the laminae interface could increase the interlaminar shear strength of carbon fiber/BMI composites by up to 58%. SEM micrographs revealed that the nanofiller successfully bridged the laminae of the composite, thus biomimicking the insect cuticle. Composite fabrication techniques developed on this program would have a wide variety of applications in space and aerospace structures including leading and trailing edges of aircraft wings.

Projectile Impact Behavior of Z-Fiber Reinforced Laminar Composites

2012 ◽  
Vol 441 ◽  
pp. 717-725 ◽  
Author(s):  
B. S. Nashed ◽  
J.M. Rice ◽  
Yong K. Kim
Keyword(s):  
Glass Fiber ◽  
Composite Laminates ◽  
Flexural Modulus ◽  
Impact Behavior ◽  
Projectile Impact ◽  
Testing Procedures ◽  
Laminar Composites ◽  
Interlaminar Shear ◽  
Strength And Stiffness ◽  
Strength Retention

The bending toughness, strength retention, resistance to damage and bending stiffness of glass fiber mat, laminar composites under high strain rate impact loading conditions was studied. One of the main disadvantages of laminar composite materials is their poor interlaminar shear strength. Recent work has demonstrated a method of Z-direction reinforcement of these composites using electrostatic flocking techniques improve delamination resistance and fracture toughness without degrading the composites tensile strength or other in-plane properties when loaded quasi-statically. The Z-direction reinforcement is accomplished by electrostatically flocking short fibers perpendicular to and between the composite ply layers. In this study, composite samples were prepared using the flocking method in two fabrication modes by the; so-called Z-Axis wet and Z-Axis dry procedures. In this work, Z-direction reinforced composite panels (including a non reinforced control) that were previously projectile impact damaged were tested using established mechanical testing procedures. Damage areas were quantified and compared using image processing techniques. Three point bending tests were also conducted on these projectile impact damaged panels to determine and compare their bending toughness, strength retention and modulus. The results show that Z-Axis reinforcement by the flocking technique improves the overall mechanical strength and stiffness properties of glass fiber mat laminar composites. For example, Z-Axis reinforced projectile damaged and not damaged glass fiber mat composite laminates are found to have flexural strengths 9% to 15% higher and a flexural modulus (stiffness) 22% to 26% higher than comparable (not Z-Axis flock reinforced) glass fiber mat samples.

Graphene Delivery Systems for Hierarchical Fiber Reinforced Composites

MRS Advances ◽  
2016 ◽  
Vol 1 (19) ◽  
pp. 1339-1344 ◽  
Author(s):  
Yan Li ◽  
Han Zhang ◽  
Ton Peijs ◽  
Emiliano Bilotti
Keyword(s):  
Glass Fiber ◽  
Epoxy Resin ◽  
Composite Laminates ◽  
Spray Coating ◽  
Fiber Reinforced ◽  
Direct Infusion ◽  
Glass Fiber Composites ◽  
Reinforced Plastics ◽  
Interlaminar Shear ◽  
Set Up

ABSTRACTThree different methods are evaluated for the introduction of graphene nanoplatelets (GNP) in hierarchical carbon- or glass fiber reinforced plastics. They involve; (1) direct infusion of GNP filled epoxy resin, (2) spray coating of GNP on fiber preforms and (3) the use of dissolvable thermoplastic interleaf carrier films. Direct infusion of GNP filled resin is the easiest method to deliver GNP into composite laminates but may lead to viscosity and filtration issues. Automated spray coating was set up to manufacture GNP modified carbon- or glass fiber fabrics, while graphene filled phenoxy interleaf films were manufactured by bar coating, both followed by resin infusion using neat epoxy resin to produce GNP modified epoxy laminates, without the disadvantages of GNP filled resins. No substantial difference in interlaminar shear strength (ILSS) for composites manufactured using the different delivery methods is found. However, the electrical conductivity of the GNP modified glass-fiber composites manufactured by spray coating of glass fabrics is two orders of magnitude higher than for laminates made by direct infusion of GNP modified resin.

An Experimental Study on the Axial Collapse Characteristics of Hybrid Side Member

2006 ◽  
Vol 324-325 ◽  
pp. 411-414
Author(s):  
Kil Sung Lee ◽  
Kwang Hee Im ◽  
In Young Yang
Keyword(s):  
Energy Absorption ◽  
Collapse Mechanism ◽  
Side Member ◽  
Specific Strength ◽  
Reinforced Plastics ◽  
Collapse Characteristics ◽  
Collapse Mode ◽  
Fiber Reinforced Plastics ◽  
Strength And Stiffness ◽  
Shaped Section

The purpose of this study was to develop lightweight hat shaped section side members which absorb the most of the energy during the front-end collision of vehicle. The hybrid side member was manufactured by combination of aluminum and CFRP. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) member is representative lightweight materials but its axial collapse mechanism is different from each other. The aluminum member absorbs energy by stable plastic deformation, while the CFRP member absorbs energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum member. Based on the respective collapse characteristics of CFRP side and aluminum members, the hybrid side members were tested on the axial collapse loads to get a synergy effect when the member is combined with the advantages of each members, such as energy absorption by the stable folding deformation of the aluminum member and by the high specific strength and stiffness of the CFRP member. Energy absorption capability and collapse mode of the hybrid side members were analyzed.

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