Characterisation and modelling friction at the tool-ply interface for thermoplastic woven composites
Press forming of thermoplastic textile composites is a 
fast and efficient method of production. Friction 
occurring between the composite material and pressure 
blank-holder during forming imparts tensile stresses in 
the sheet which help counteract compressive stresses 
generated by material deformation; stresses that can 
result in unwanted wrinkling of the forming sheet. In 
order to model the press forming process and optimise 
boundary conditions, this friction behaviour must be 
characterised and modelled. Two different test methods 
are employed to characterise the friction and two 
complementary modelling strategies, an empirical and a 
predictive approach, are presented.
Composite preforming defects: a review and a classification
Advancing in the process of extending the use of composites for structural parts applications, it is inevitable to work on complex shapes. That is the main reason why understanding the complex forming mechanisms and the factors put into play during the process of composite materials is a major interest for both pre-impregnated forming and dry fabric preforming. Thus, the appearance of defects is a major concern and predicting their appearance for optimal product quality is the priority. A great number of authors showed that defects degrade the overall performance of the composite by creating local heterogeneities. Many factors can initiate these defects. This article is an assembly of the development of the literature on this subject. It is an attempt to provide a description for each defect and a classification order following the scale, the behavior mechanisms, the appearance plan. This will help to converge toward an identification of the defects manifesting during the composite forming.
Formation of unexpected ions from a first-generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?
We report the formation of unexpected ions during the analyses of a first-generation polyamidoamine dendrimer in negative ion mode using an ion trap equipped with an electrospray ionisation source. These surprising ions corresponded to an increase of 12 m/z units over those expected. The formation of the unexpected ions was dependent on the tuning of the solution flow rate and the capillary high voltage. In addition, measurements of unusual value of the current suggested that a reaction was occurring in the corona plasma. The influence of methanol in this phenomenon was demonstrated by using CD(3)OH in the sample preparation. We propose two structures to explain the observed adduct based on the results of MS(2) experiments and by referring to previous work dealing with 12 m/z units addition. We showed that a corona discharge caused by alterations taking place to the electrospray capillary emitter was the origin of these unexpected ions. Finally, we discuss the mechanism involved in the formation of the ions and we propose means to control such artefacts.