Article Debonding of composites structural insulated sandwich panels Mohammed A Mousa and Nasim Uddin Abstract A new type of composites structural insulated panels (CSIPs) is presented in this article. These panels are proposed for structural floor and wall applications. The developed composite panels are made of low-cost orthotropic thermoplastic glass/polypropylene laminate as facesheets and expanded polystyrene foam as a core. CSIPs have a considerably high facesheet/core moduli ratio. The common mode of failure of these panels is facesheet/core debonding. Accordingly, this investigation presents models for interfacial tensile stress and critical wrinkling in-plane stress associated with debonding of CSIPs. The facesheet in compression was modeled as a beam on a Winkler foundation. The proposed models were validated using full-scale experimental testing for CSIPs floor and wall panels. Both type of panels failed by facesheet/ debonding with natural half-wavelength approximately equal to the core thickness. Keywords Sandwich structures, facesheet/core debonding, wrinkling, thermoplastic composites Notation b panel width t thickness of glass-pp facesheet L panel length c core thickness d total thickness of sandwich panel l natural half-wavelength of the debonded part w m out-of-plane displacement of the debonded part ' z out-of-plane interfacial tensile stress ' cr in-plane critical wrinkling stress E f longitudinal modulus of elasticity of glass-pp facesheets E c core modulus of elasticity G core shear modulus ) xy Poisson’s ratio of facesheet in the xy-plane Introduction Sandwich structures consist of two stiff, thin facing, and lightweight thicker core. The concept of the sand- wich structures is similar to that of I-sections, in which facesheets carry the bending stresses while the core resists the shear loads and stabilizes the faces against bulking or wrinkling. 1 The core also increases the stiffness of the structure by holding the facesheets apart. In general, core materials have lower mechanical properties compared to that of facesheets. For ordinary sandwich panels used in construction, the common core/facesheet thickness ratio ranges from 10 to 50 while the moduli ratio varies from 50 to 1000. 1 This article presents new a composite panel system, namely, composite structural insulated panels (CSIPs), which are developed by the authors. CSIPs are made of low-cost orthotropic thermoplastic glass/ polypropylene (glass-PP) laminate as facesheets and expanded polystyrene foam (EPS) as a core. Thermoplastics (TP) polymers offer advantages in terms of short processing time, extended shelf life, and low-cost raw material. TP also possess the advan- tages of high toughness, superior impact property, and ease of reshaping and recycling over thermoset polymer composites. Several investigations have been conducted Department of Civil, Construction and Environmental Engineering, University of Alabama at Birmingham, USA. Corresponding author: Mohammed A Mousa, Department of Civil, Construction and Environmental Engineering, University of Alabama at Birmingham, Birmingham, AL 35294-4440, USA Email: [email protected] Journal of Reinforced Plastics and Composites 29(22) 3380–3391 ! The Author(s) 2010 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0731684410380990 jrp.sagepub.com
Debonding of composites structural insulated sandwich panels
Jun 24, 2023
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