Papers by Keyword: GRP

Abstract: Within the research project a variable gridshell in lightweight design was developed that permit the building of free-formed mobile architectures. The construction consists of a large number of straight length-adjustable bars pin-jointed via so-called knots and enables extremely efficient and stable support structures with high potential for lightweight construction.

Abstract: Fiber-reinforced plastics (FRP) are of great importance for the transport sector, the aerospace industry, for wind power plants, in the building sector and in the field of sports and leisure applications. Optimization of the adhesive bonding process for FRP structures, especially the surface preparation prior to bonding, will be of a central importance in forthcoming expansion of FRP use. In this connection the key problem depends on the FRP polymer matrix. In the case of duroplastic matrix the main problem is the presence of release agent on the surface of joining components. For the thermoplastic matrix such as polypropylene (PP), the main problems are the low surface energy and the inertness of its surface. Conventional pretreatment methods, such as manual grinding, shall be replaced by energetic radiation technics like VUV lamps (vacuum ultraviolet spectral range: 100 – 200 nm). This approach is a non-contact method, characterized by high treatment homogeneity and material-saving properties, combined with no further fibers to be released. The surface of the thermoplastics is activated by the incorporation of oxygen, release agent contamination on the thermoset is cleaned or modified [1 - 8]. The results of the VUV surface activation of PP and CFRP with regard to the incorporation of functional groups, increase of surface energy, matrix degradation and the adhesion increase of adhesive bonds are presented. In addition, studies on the release agent coating and the release agent modification by VUV radiation are presented. The work is completed by considerations concerning possibilities to accelerate the process (in particular, wavelength dependence, influence of an inert gas or the moisture content). Finally, an evaluation of the VUV pretreatment is carried out on the basis of two specific applications.

Abstract: The marine industry at present employs the use of aluminium extrusions in the construction of decks and superstructures that could be replaced with pultruded glass reinforced plastic (GRP) profiles. The length of the pultruded section is limited and therefore, efficient and economic jointing techniques must be developed that can withstand the loads applied to ship structures. This paper evaluates a novel means of adhesively bonded connection for GRP structures known as a finger joint. Various joint geometries are examined, load displacement behaviour is established and Thermoelastic Stress Analysis (TSA) is used to provide the full field stress distribution over the joint. The results of the TSA are compared with the load displacement behaviour. It is shown that by increasing fingertip angle there is a decrease in load carrying capacity, a decrease in shear stress and an increase in stress concentration factor at the finger joint tip.