Prediction of Moisture and Temperature Changes in Composites During Atmospheric Exposure

et al. 2006

Fiber-reinforced glass-epoxy composites with and without prior thermal history are subjected to hygrothermal conditioning for different exposure times. The prior thermal history is given in the form of thermal shocks and thermal spikes at three different temperatures. The effects of exposure time and prior thermal history on the moisture absorption kinetics are studied. The effects of prior conditioning parameters are also investigated. The variation of mechanical properties as a function of exposure time and prior conditioning parameters are assessed by the three-point short beam shear bend test. It has been observed that there is an initial improvement in the mechanical properties followed by a steady deterioration. Mechanical tests performed at different crosshead velocities show increasing brittleness of the composites and that is found to be a function of cross-head velocity.

Section: Resultsmentioning

confidence: 99%

Section: Ilss (Mpa)mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Prior Thermal Spikes and Thermal Shocks on Mechanical Behavior of Glass Fiber-Epoxy Composites

et al. 2006

“…Surface absorption and diffusion through the matrix is the primary mechanism for moisture pick-up in most of the well-fabricated composite materials during the initial period of exposure [10]. The composite materials contain cracks and microvoids in the matrix.…”

Section: Resultsmentioning

confidence: 99%

Effects of Thermal Shocks and Thermal Spikes on Hygrothermal Behavior of Glass—Polyester Composites

et al. 2007

The aim of the present study is to investigate the degradation behavior of glass fiber reinforced polyester composites during hygrothermal ageing for different lengths of time after suffering thermal shocks and thermal spikes at 100, 150, and 200°C. The moisture gain kinetics and change of interlaminar shear strength (ILSS), a primary mode of analysis of interfacial strength of the composite, were evaluated. Moisture absorption, found more in spiked samples, showed initial Fickian trend but eventually changed to non-linear pattern as the exposure time increased. It has been found that the composite specimens having a history of thermal spike showed more degradation. The damage was found even more at higher temperature and at lower loading rates.

“…It changes continuously, with the water concentration depending on time and position [10]. The level of adhesion between fibers and matrix affects the ultimate mechanical properties of the composite -both parallel to the direction of fibers as well as off-axis [14]. Shear failure in the interphase could be caused by interfacial shear failure between the fiber and interphase itself [15].…”

Section: Resultsmentioning

confidence: 99%

Effects of Hydrothermal Aging on Mechanical Behavior of Sub-zero Weathered GFRP Composites

et al. 2006

Sub-zero weathered GFRP (glass fiber reinforced plastics) composites were aged in water at 60 C for different conditioning times to study fluid sorption kinetics under the influence of a thermal gradient. The effect of subsequent freezing of the conditioned samples on the retention of prior thermal history has been investigated. The variation in mechanical properties during the aging process was studied. One batch of the hydrothermally conditioned specimens was further subjected to sub-zero treatment at 20 C temperature. The samples which were subsequently frozen showed higher interlaminar shear strength (ILSS) initially, although this trend was reversed after a certain conditioning period. Thus, the present study aims to evaluate the mechanical behavior of polymer composites under the influence of extreme and complex conditions.