Mikael Petersson

Bio: Mikael Petersson is an academic researcher from Saab AB. The author has contributed to research in topics: Composite number & Flange. The author has an hindex of 13, co-authored 51 publications receiving 446 citations.

An experimental study of mechanisms behind wrinkle development during forming of composite laminates

Abstract: A general problem when forming quasi-isotropic, multilayer unidirectional (UD) prepreg over a double curved geometry is out-of-plane wrinkling. The presented study aims to show the existence of com ...

A method of manufacturing an elongate structural element configured for stiffening a shell structure, and a method for manufacturing a rigid shell structure integrated with at least one elongate stiffening element

Abstract: Method for manufacturing an elongate structural element and a rigid shell structure integrated with at least one elongate stiffening element. The method includes the steps of providing a preformed, form-stable former (16), which has a hat profile with two inwardly directed, opposing flange portions (20), covering the former with a curable composite material to form an external hat profile (24, 26) having outwardly directed flanges (26), and integrating this assembly (16, 24, 26) with either a curable or preformed shell structure (10) of composite material.

Interface manipulation towards wrinkle-free forming of stacked UD prepreg layers

Abstract: The aim of this paper is to experimentally study how forming behaviour can be changed by local manipulation of prepreg interfacial characteristics. Different methods for surface modification are ex ...

Method for fabricating a curved beam from composite material

Abstract: A method for fabricating a curved beam from fiber composite material. A flat fiber composite laminate including a plurality of layers and at least two different fiber directions is formed. The fiber composite laminate is disposed in contact with a male tool includes a first flange, a second flange and an intermediate web. The male tool is curved in its longitudinal direction with a radius of curvature in such a way that the first flange has a shorter longitudinal extent than the second flange. The fiber composite laminate is brought into contact with and secured to the first flange of the male tool. The male tool and the fiber composite laminate are then rotated relative to one another so that the fiber composite laminate is brought into contact with the intermediate web of the male tool in a first rotational movement, and brought into contact with the second flange of the male tool in a second rotational movement. The fiber composite laminate hardens on the male tool, and the finished beam is separated from the tool. Also a beam of fiber composite material fabricated according to the method.

A method of manufacturing an integral article comprising a fiber-reinforced composite material, and a tool assembly for making the same

Abstract: The invention relates to a method of manufacturing an integral article comprising a fiber-reinforced composite material. An inner tool body (12) of a cellular plastic material is provided, onto which an airtight sheet (14) of a flexible material is applied so as to fully encompass and seal the tool body (12). A plurality of layers (16) of fiber-reinforced composite material are then applied onto the outer surface of the airtight sheet (14), and an airtight vacuum bag (18) is in turn applied onto the outer layer of the composite material (16). The vacuum bag (18) is evacuated and the layers (16) of composite material compressed. The composite material is heat treated so as to cure the same. The vacuum bag (18) is then removed from the thus formed article. To form a hollow integral tank, the formed article is provided with a hole (22), and a solvent is poured therein to dissolve the cellular plastic material. The dissolved material is then drained through the hole (22), and the airtight sheet (14) is possibly removed theretrough.

The bias-extension test for the analysis of in-plane shear properties of textile composite reinforcements and prepregs: a review

Abstract: The bias-extension test is a rather simple experiment aiming to determine in-plane shear properties of textile composite reinforcements. However the mechanics during the test involves fibrous material at large shear strains and large rotations of the fibres. Several aspects are still being studied and are not yet modeled in a consensual manner. The standard analysis of the test is based on two assumptions: inextensibility of the fibers and rotations at the yarn crossovers without slippage. They lead to the development of zones with constant fibre orientations proper to the bias-extension test. Beyond the analysis of the test within these basic assumptions, the paper presents studies that have been carried out on the lack of verification of these hypothesis (slippage, tension in the yarns, effects of fibre bending). The effects of temperature, mesoscopic modeling and tension locking are also considered in the case of the bias-extension test.

Formability analyses of uni-directional and textile reinforced thermoplastics

Abstract: The formability of two different composite materials used in aerospace industry has been investigated for a representative product geometry. The deformations during forming of carbon UD/PEEK and glass 8HS/PPS blanks with a quasi-isotropic lay-up were analysed. The UD/PEEK product showed severe wrinkling in doubly curved areas, whereas the 8HS/PPS product showed better formability in those areas. This can be explained by the relatively high resistance against intra-ply shear for the UD/PEEK material. Moreover, the predictive capability of a finite element based simulation tool was shown. For both materials, the prediction of intra-ply shear and large wrinkles showed good agreement with those observed in the actual product. The smaller wrinkles in the products cannot be accurately represented with the element size used. However, predicted waviness at the corresponding locations could indicate critical areas in the product. The presented modelling approach shows great potential for application in the composite product design process.