An experimental investigation on mechanisms for manufacturing induced shape distortions in homogeneous and balanced laminates

Svanberg, Jonas; Holmberg, J. Anders

doi:10.1016/s1359-835x(00)00173-1

Cited by 102 publications

(66 citation statements)

References 11 publications

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“…Apparently, this 'constraint-induced strain' was irreversible. Recently, Svanberg and Holmberg [13] suggested the concept of 'frozen-in strain' by mold constraint without experimental evidence to explain spring-in deformation of an angle section beam manufactured by the RTM process. Figure 11 shows the final residual strains of the unidirectional laminates manufactured by the three cure cycles.…”

Section: Resultsmentioning

confidence: 99%

Cure Cycle Effect on Composite Structures Manufactured by Resin Transfer Molding

Kim

Daniel

2002

Journal of Composite Materials

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An experimental investigation was conducted of the effect of curing cycle on the development of material properties, residual strains and stresses in composite parts during the resin transfer molding (RTM) process. The material investigated consisted of AS4 carbon fibers as the preform and a three-part epoxy system. Unidirectional and crossply carbon/epoxy laminates were prepared by the RTM process in aluminum molds. Several different curing cycles were designed by changing the peak cure temperature and heat up rate based on a cure kinetic model. Strains were measured in the composite laminates during curing using embedded fiber optic strain sensors and electrical resistance strain gages. It was found that significant strain was developed by interference between composite and mold during cure, resulting in constraint-induced strain. The magnitude of residual stresses was also assessed by measuring the warpage curvature of asymmetric cross ply laminates. The data showed that the residual stress was significantly dependent on the cure cycle and the interference.

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Section: Resultsmentioning

confidence: 99%

Cure Cycle Effect on Composite Structures Manufactured by Resin Transfer Molding

Kim

Daniel

2002

Journal of Composite Materials

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“…As a consequence to their multilayered structure they show high anisotropy, which complicates NDT. Defects specific to these materials are holes in the fabric, pores, delaminations, contamination of the surface effectively weakening the material and residual stresses [6][7][8]. Those defects can be found with conventional ultrasound when using high testing frequencies.…”

Section: Defects Detectable With Ondtmentioning

confidence: 99%

Novel trends in optical non-destructive testing methods

Huke

Klattenhoff

Kopylow

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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Non-destructive testing (NDT) describes a wide range of methods for measuring and comparing physical quantities against a nominal condition. In this paper we describe and compare different optical NdT (ONDT)-methods with respect to their characteristics and capability for different measurement tasks. ONDT may be specified in two categories, passive and active. The NDT principles of the first category just use a measurement method like view inspection, elipsometry or reflectometry to detect defects which are easily accessible. The principles of the second category use an excitation force, such as heat or mechanical vibration introduced by transducers to detect hidden defects. This category can be specified into two subcategories. The first subcategory "time-/depth-resolved" includes measurement methods delivering detailed information of the geometric features of a hidden defect. Therefore the excitation of the material and the detection of the reaction have to provide a time step which enables depth-solved measurements. Phase-resolved thermography and laser ultrasound are examples for this category. The second subcategory "Integrating" includes measurement technique coupled with an excitation that enables detection of defects but not evaluation of their geometric features. Examples for these measurement techniques are shearography, reflectometry, vibrometry and thermography coupled with excitation method like simple heating or loading with a constant force. We demonstrate experimental results obtained using methods developed in our institute and highlight directions of further development.

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“…Their predicted and measured spring-in values were correlated for [0]24 layup; however the correlation was bad for [90]24. (Svanberg and Holmberg, 2001,2004and Svanberget et al,2005) developed a simplified mechanical constitutive model to predict the shape distortions. They assumed that the mechanical behaviour of the material is constant within rubbery and glassy states and there is a step change in the properties at the glass transition temperature.…”

Section: Introductionmentioning

confidence: 99%

İsti̇fleme Açisinin Fi̇ber Takvi̇yeli̇ Kompozi̇t Plakalarda Çarpilmaya Etki̇si̇

Çınar¹

2015

EJOVOC Electronic Journal of Vocational Colleges

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ÖzetFiber takviyeli kompozit malzemeler pişirme süreci sonrasında kalıptan ayrıldığında tasarlandığı şekilden farklı bir şekil almaktadır. Üreticilerin kullandığı deneme yanılma yöntemleri ile toleranslar içerisinde kompozit parçalar üretilmekte fakat bu yöntem pahalı ve zaman alıcıdır. Bu problemin çözümü mutlak şekil değişimini tahmin etmek ve sonra istenilen son şekil değişimini veren kalıbı tasarlamaktır. Bundan dolayı düz parçaların üretim sırasında çarpılmasını ön gören 3 boyutlu bir sonlu elemanlar modeli geliştirilmiştir. Bunun yanında istiflenme açısının çarpılmaya etkisi incelenmiştir.Anahtar Kelimeler: Sonlu elemanlar yöntemi, kompozit malzemeler, süreç modellenmesi, artık gerilmeler. EFFECT OF STACKING SEQUENCE ON THE WARPAGE OF FIBER REINFORCED COMPOSITE PLATES AbstractA fibre reinforced composite part generally takes a different shape from the one that is originally designed after removing from the mould at the end of the curing process. Traditional method used by manufacturers is a trial and error approach to fabricate the composite parts within the dimensional tolerances but this method is very expensive and time consuming. The solution of this problem is to predict the absolute magnitude of the distortion and then to design a mould that gives the desirable final shape according to the prediction. Thus a 3D Finite Element (FE) model was developed to predict the warpage values occur during manufacturing of flat laminates. In addition, the effect of stacking sequence on warpage was investigated.

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An experimental investigation on mechanisms for manufacturing induced shape distortions in homogeneous and balanced laminates

Cited by 102 publications

References 11 publications

Cure Cycle Effect on Composite Structures Manufactured by Resin Transfer Molding

Cure Cycle Effect on Composite Structures Manufactured by Resin Transfer Molding

Novel trends in optical non-destructive testing methods

İsti̇fleme Açisinin Fi̇ber Takvi̇yeli̇ Kompozi̇t Plakalarda Çarpilmaya Etki̇si̇

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