Composites science and technology

Voids, the most studied type of manufacturing defects, form very often in processing of fiber-reinforced composites. Due to their considerable influence on physical and thermomechanical properties ...

https://journals.sagepub.com/doi/pdf/10.1177/0021998318772152

Voids in fiber-reinforced polymer composites: A review on their formation, characteristics, and effects on mechanical performance:

Reference EPFL-ARTICLE-184271doi:10.1016/j.compositesa.2012.08.001View record in Web of Science Record created on 2013-02-27, modified on 2017-05-10

Composites Part A: Applied Science and Manufacturing

This paper investigates comprehensive knowledge regarding joining CFRP and aluminium alloys in available literature in terms of available methods, bonding processing and mechanism and properties. The methods employed comprise the use of adhesive, self-piercing rivet, bolt, clinching and welding to join only CFRP and aluminium alloys. The non-thermal joining methods received great attention though the welding process has high potential in joining these materials. Except adhesive bonding and welding, other joining methods require the penetration of metallic pins through joining parts and therefore, surface preparation is unimportant. No model is found to predict the properties of jointed structures, which makes it difficult to select one over another in applications. The choice of bonding methods depends primarily on the specific applications. The load-bearing mechanism of bolted joints is predominantly the friction that is the first stage resistance. Hybrid joints performance is enhanced by combining rivets, clinch or bolts with adhesives.

/pdf/joining-of-carbon-fibre-reinforced-polymer-cfrp-composites-b1dn74dni2.pdf

Joining of carbon fibre reinforced polymer (CFRP) composites and aluminium alloys-A review

Bistable plates for morphing structures: A refined analytical approach with high-order polynomials

Unidirectional non-crimp fabrics (UD-NCF) are often used to exploit the lightweight potential of continuous fiber reinforced plastics (CoFRP). During the draping process, the UD-NCF fabric can undergo large deformations that alter the local fiber orientation, the local fiber volume content (FVC) and create local fiber waviness. Especially the FVC is affected and has a large impact on the mechanical properties. This impact, resulting from different deformation modes during draping, is in general not considered in composite design processes. To analyze the impact of different draping effects on the mechanical properties and the failure behavior of UD-NCF composites, experimental results of reference laminates are compared to the results of laminates with specifically induced draping effects, such as non-constant FVC and fiber waviness. Furthermore, an analytical model to predict the failure strengths of UD laminates with in-plane waviness is introduced. The resulting stiffness and strength values for different FVC or amplitude to wavelength configurations are presented and discussed. In addition, failure envelopes based on the PUCK failure criterion for each draping effect are derived, which show a clear specific impact on the mechanical properties. The findings suggest that each draping effect leads to a “new fabric” type. Additionally, analytical models are introduced and the experimental results are compared to the predictions. Results indicate that the models provide reliable predictions for each draping effect. Recommendations regarding necessary tests to consider each draping effect are presented. As a further prospect the resulting stiffness and strength values for each draping effect can be used for a more accurate prediction of the structural performance of CoFRP parts.

The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites.

Processing Studies for the Development of a Manufacture Process for Intelligent Lightweight Structures with Integrated Sensor Systems and Adapted Electronics

Studies on the Characterization of Novel Piezoelectric Sensor Elements, Integrated in Glass Fibre-reinforced Polyurethane Composites

Accessing pore microstructure–property relationships for additively manufactured materials

For a reliable structural design of security-relevant, high-dynamically loaded light weight structures, the knowledge of the strain-rate-dependent material and damage behaviour, material properties, and validated material models have to be provided. For this purpose, various material tests at different strain rates have been performed on composites with a novel 3D-reinforced glass-fibre multilayered flat-bed weft-knitted fabric reinforcement by using a servohydraulic high-speed testing unit in combination with specially adapted clamping de vices. The highly dynamic material tests served to develop adequate material models in the classical sense of continuum damage mechanics and to determine the associated model parameters.

Maik Gude

Papers

The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites.

Processing Studies for the Development of a Manufacture Process for Intelligent Lightweight Structures with Integrated Sensor Systems and Adapted Electronics

Studies on the Characterization of Novel Piezoelectric Sensor Elements, Integrated in Glass Fibre-reinforced Polyurethane Composites

Accessing pore microstructure–property relationships for additively manufactured materials

The strain-rate-dependent material and failure behaviour of 2D and 3D non-crimp glass-fibre-reinforced composites