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

A novel approach to the manufacture of adaptive composite structures with integrated piezoelectric modules focusses on combining the previously separate production steps – production of the piezoceramic transducer, composite fabrication and integration of the transducers – into an efficient single-stage process Based on the long fibre injection (LFI) technology, a novel multi fibre injection (MFI) method is developed By integrating piezoceramic components like short fibres or pearls and suitable electrode structures into the composite, novel piezoelectric functional elements are created and embedded during the structure's manufacturing process For the functionalisation of these elements, mainly to provide sensory properties, poling of the piezoceramic components during or after the production process is required Based on initial simulations of electric field strength, poling process and resulting small signal properties, conclusions for an adapted poling strategy of these novel sensor modules are elaborated

Studies on the polarisation behaviour of novel piezoelectric sensor modules

In this study, a new joining technology to produce hybrid structures with continuous-fiber-reinforced thermoplastics and metallic components is presented adapting the concept of classical clinching for thermoplastic composites. To demonstrate the capability of the thermoclinching process, prototypic joints were manufactured using an experimental joining installation developed. Nondestructive and destructive analyses of the thermoclinched joints showed that a relocation of the reinforcement into the neck and head area of the joining zone could be achieved. For a first estimation of the maximum load-carrying capacity of the joints, single-lap specimens with both reinforced and nonreinforced thermoplastics were manufactured and tested, revealing up to 50% higher failure loads of the reinforced joints. To understand the local material configuration and to achieve a defined and adjustable fabric structure in the head area of the joint, further analyses with regard to material- and tool-side conditions of the joining zone are necessary.

Simulation of a Novel Joining Process for Fiber-Reinforced Thermoplastic Composites and Metallic Components

The rate-dependent failure response of multi-material adhesive joints for three deformation modes is investigated. A combination of carbon fibre reinforced polymers (CFRP) and titanium alloy Ti-6Al-4V is employed. The experiments provide important information about the failure sequence of a multi-material adhesive joints, which depends upon the loading rate regime. This is the first time that dynamic fracture mechanics experiments are performed in multi-material adhesive structures. The observed experimental results suggest a rate-dependent failure sequence for mode I dominated fracture. Simulations of the experiments are used to predict and rationalise the failure performance of the multi-material adhesive joint. The numerical analysis highlighted the importance of the individual knowledge of the rate-dependent mechanical performance of adhesive and composite to fully understand the fracture sequence of multi-material joints under impact.

/pdf/multi-material-adhesively-bonded-structures-characterisation-8q45zhyibp.pdf

Multi-material adhesively bonded structures: Characterisation and modelling of their rate-dependent performance

Metallic (M) and polymer (P) materials as layered hybrid metal-polymer-metal (MPM) sandwiches offer a wide range of applications by combining the advantages of both material classes. The interfaces between the materials have a considerable impact on the resulting mechanical properties of the composite and its structural performance. Besides the fact that the experimental methods to determine the properties of the single constituents are well established, the characterization of interface failure behavior between dissimilar materials is very challenging. In this study, a mixed numerical–experimental approach for the determination of the mode I energy release rate is investigated. Using the example of an interface between a steel (St) and a thermoplastic polyolefin (PP/PE), the process of specimen development, experimental parameter determination, and numerical calibration is presented. A modified design of the Double Cantilever Beam (DCB) is utilized to characterize the interlaminar properties and a tailored experimental setup is presented. For this, an inverse calibration method is used by employing numerical studies using cohesive elements and the explicit solver of LS-DYNA based on the force-displacement and crack propagation results.

Maik Gude

Papers

Studies on the polarisation behaviour of novel piezoelectric sensor modules

Simulation of a Novel Joining Process for Fiber-Reinforced Thermoplastic Composites and Metallic Components

Multi-material adhesively bonded structures: Characterisation and modelling of their rate-dependent performance

A Mixed Numerical-Experimental Method to Characterize Metal-Polymer Interfaces for Crash Applications

Process-integrated embedding of metal inserts in continuous fibre reinforced thermoplastics