Abstract. The short and long term creep behavior is one of the most important properties of polymers used for engineering applications. In order to study this kind of behavior of PP tensile and short term creep measurements were performed and analyzed using long term creep behavior estimating method based on short term tensile and creep tests performed at room temperature, viscoelastic behavior, and variable transformations. Applying Weibull distribution based approximations for the measured curves predictions for the creep strain to failure depending on the creep load were determined and the parameters were found by fitting the measurements. The upper, mean, and lower estimations as well as the confidence interval for the means give a possibility for designers' calculations at arbitrary creep load levels.

In this paper the creep of short (chopped) basalt fibre reinforced Poly(Lactic Acid) (PLA) composites was investigated. 5, 10, 20 and 30wt% short basalt fibre reinforced composites were prepared by using twin-screw extrusion followed by injection moulding. Differential Scanning Calorimetry (DSC) measurements revealed that the basalt fibres had nucleating effect on the PLA grade used in this study, 3

When fiber-reinforced plastic (FRP) components are designed, it is very important to ensure that textiles are formed into complex 3D geometries without folds, and that the reinforcing structure is oriented appropriately. Most research in this context is focused on finite element (FE) forming simulations and the required characterization of textile reinforcements. However, the early stage of the design of FRPs, where kinematic draping simulations are used, is barely considered. In particular, the need for a critical shear angle for the execution and evaluation of kinematic draping simulations is often neglected. This paper presents an extended picture frame test stand with an optical device recording shear-induced deformations with the help of a laser line emitter. Associated hardware and software for detecting and quantifying the fold formation during a picture frame test were developed. With the additional recorded information, a material-specific critical shear angle can be determined, material behaviors can be compared, and FE-based simulation methods can be evaluated. This innovative test stand and the associated software tools will help engineers to decide on suitable materials and improve transparency in the early stages of the design process.

In this paper tensile and creep tests were performed on polypropylene (PP) and its glass fiber reinforced composites. The tensile tests were carried out on 6 different glass fiber content reinforced PP composites (0, 5, 10, 20, 30 and 40%) while the creep tests were performed on the unreinforced and 30% and 40% fiber reinforced ones of industrial importance. 50 N/s constant force rate was used until the specimen failed (tensile test) or the preset load level was reached (creep test). The applied load levels for the creep experiments were determined as given ratios of the average breaking force. The tensile breaking strain and tensile strength versus fiber content relationship were analyzed and described by empirical formulas based on the correction and averaging procedure developed.

In order to study the short-and long-term creep behaviours of injection moulded, unreinforced and glass fibre reinforced polypropylene composites, tensile and creep measurements were carried out and analysed. Based on the linear viscoelastic behaviour and variable transformations as well as Weibull-based distribution characterisation, estimations for the tensile strength parameters and creep failure strain were determined and fitted to the measurements. These mathematical estimations and the relationships between the material model czonstants and the fibre content, determined by fitting, give a possibility for designers' calculations at arbitrary creep load levels and fibre contents.