Determination of residual stresses in GFRP composite using incremental slitting method by the aid of strain gauge

Umarfarooq, M. A.; Gouda, P.S. Shivakumar; Nandibewoor, Archana; Banapurmath, N. R.; Kumar, G. B. Veeresh

doi:10.1063/1.5085609

Cited by 5 publications

(5 citation statements)

References 20 publications

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“…Under these conditions, the stresses along the fibers reached 40-60 MPa. Similar results substantiating the formation of cracks, shrinkage, and interlayer fracture were obtained in [26,[33][34][35][36][37].…”

Section: Causes For Internal Stresses In Pcmssupporting

confidence: 86%

The Influence of Internal Stresses on the Aging of Polymer Composite Materials: a Review

Каблов

Startsev

2021

Mech Compos Mater

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The formation of internal stresses in polymer composite materials (PCMs) caused by different elastic moduli and thermal expansion coefficients of polymer resin and reinforcing fibers, as well as by swelling due to the moisture uptake is discussed. The influence of thermal cycles on the internal stresses and strength of the materials was studied in dry and wet atmospheres. It shown that thermal cycles cause a periodic jumps in the stresses at lowfrequency mechanical loadings, during which the mechanical properties are degraded due to the formation of microscopic cracks in the polymer matrix. The relative changes in the strength, elastic modulus, glass-transition temperatures, moisture diffusion coefficient, and other PCM physical characteristics are proportional to the logarithm of the number of cycles and also depend on the form and size of specimens, amplitude, conditions, and length of thermal cycles. A prolonged action of external actions relaxes the internal stresses and reduces their influence on the aging of PCMs.

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Section: Causes For Internal Stresses In Pcmssupporting

confidence: 86%

The Influence of Internal Stresses on the Aging of Polymer Composite Materials: a Review

Каблов

Startsev

2021

Mech Compos Mater

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“…Various methods for creating the slit have been used from the basic approach of using a thin saw blade [14,[48][49][50][51][52] to using focused ion beams [42,46,53,54] and an electron discharge machine (EDM). [45,55] One obvious problem of using a saw, a mill or any other abrasive method is that it will invariably introduce additional stresses into the specimen being tested.…”

Section: The Slitting Methodsmentioning

confidence: 99%

Residual stress in fiber reinforced thermosetting composites: A review of measurement techniques

2021

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Residual stress is inherent in any fiber reinforced composite, created by the laminates processing route and high levels of anisotropy. The aim of this article is to provide an up to date review of the current state of the art in experimental techniques for the determination of residual stress in thermosetting fiber reinforced composites. Residual stress is considered at a micro-mechanical, macro-mechanical, and global scale as each require specific techniques to investigate and offer their own unique challenges to the designer. Many advances have been made in the experimental determination of residual stress in fiber reinforced composites since the last comprehensive review of the topic by Shokrieh in 2014. However, more work still needs to be done to develop a method that is applicable to all cases and can be applied as a universal standard. It remains a significant challenge to experimentally determine residual stress in thermosetting composites.

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“…Destructive methods of residual stress measurements are based on the principle of estimating stresses from deformations/strains, which are released when the stressed specimen is locally machined. The slitting method [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], also known as the crack compliance method, is one of the most commonly used destructive methods. It involves machining a narrow slit through a stressed sample and the released strains are measured using a strain gage bonded across the adjacent material.…”

Section: Mechanical Testsmentioning

confidence: 99%

“…The recorded strains and the residual stresses for each incremental cut can be expressed in matrix form as:

where [ C ] is the compliance coefficient matrix,

is the vector of residual stress and

—vector of recorded strain compliance coefficients were determined by simulating the experimental slitting process of the composite specimen using FE analysis. The simulation was carried out using ANSYS software with the experimentally determined elastic constants of GE and CE laminates* using the procedure detailed in the earlier reported works [ 13 , 18 , 20 , 21 , 22 , 23 , 24 , 25 ]. The specific element of compliance matrix C ij corresponds to strains measured across the strain gauge when the applied residual stresses are equal to the unit load.…”

Section: Mechanical Testsmentioning

confidence: 99%

On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites

et al. 2022

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The resistance to delamination in polymer composite depends on their constituents, manufacturing process, environmental factors, specimen geometry, and loading conditions. The manufacturing of laminated composites is usually carried out at an elevated temperature, which induces thermal stresses in composites mainly due to a mismatch in the coefficient of thermal expansion (CTE) of fiber and matrix. This work aims to investigate the effect of these process-induced stresses on mode-I interlaminar fracture toughness (GI) of Glass-Carbon-Epoxy (GCE) and Glass-Epoxy (GE) composites. These composites are prepared using a manual layup technique and cured under room temperature, followed by post-curing using different curing conditions. Double cantilever beam (DCB) specimens were used to determine GI experimentally. The slitting technique was used to estimate residual stresses (longitudinal and transverse direction of crack growth) inherited in cured composites and the impact of these stresses on GI was investigated. Delaminated surfaces of composites were examined using a scanning electron microscopy (SEM) to investigate the effect of post-curing on the mode-I failure mechanism. It was found that GI of both GE and GEC composites are sensitive to the state of residual stress in the laminas. The increase in the GI of laminates can also be attributed to an increase in matrix deformation and fiber–matrix interfacial bond with the increase in post-curing temperature.

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Determination of residual stresses in GFRP composite using incremental slitting method by the aid of strain gauge

Cited by 5 publications

References 20 publications

The Influence of Internal Stresses on the Aging of Polymer Composite Materials: a Review

The Influence of Internal Stresses on the Aging of Polymer Composite Materials: a Review

Residual stress in fiber reinforced thermosetting composites: A review of measurement techniques

On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites

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