Deformability of expanded polystyrene under short-term compression

Prediction of creep strain in mineral wool slabs under compression

“…In this paper, the regression equations (6) and (7) ((t i =10) years), then the error, related to the fact that the test limits relation form will change slightly, will be small and may be covered with a confidence interval (Gnip et al 2007). Extrapolating from the equation (6), obtained creep deformation patterns for prediction for up to 10 years can be sufficiently predicted using the relative creep deformations at time t which under constant compressive stress σ c are calculated per unit stress and are called creep mobility: showing experimental values variation of stone wool creep deformations which have been by 92% dependent on compressive stress changes and specific values of deformations (corresponding to the start of significant decrease in the initial firmness of the product), and by 8% -on other factors the influence of which has not been assessed yet in the adopted scheme.…”

“…3.- (Gnip et al 2007). If it is solved, in case of two prediction results, we obtain: the influence coefficients for joint prediction results:…”

“…However, such data practically cannot be found in literature, because these experiments are complex and long-term, it is important to carry out short-term tests and extrapolate obtained results for a longer time (Žiliukas 2004;Gnip et al2007Gnip et al , 2009. Moreover, if in the case of expanded polystyrene products their mechanical properties with the confidence level of 90-95% may be related with their density (Gnip et al2005(Gnip et al , 2007(Gnip et al , 2012bVaitkus 2007;Mihlaynlar et al 2008), in the case of stone wool products such data cannot be easily systemized due to anisotropic structure, especially when it is crimped (Bergonnier et al 2005;Karamanos 2007; Gnip et al 2009) because compressive and other loads are received by unevenly distributed inter fibre contacts (Gnip et al 2012b). Mechanical behaviour of stone wool products under long-term loads is significantly different from the behaviour of the material under short-term loads (Merkel 2002).…”

Stability of Strength and Deformation Characteristics of Expanded Polystyrene (EPS) within the Time of Long-Term Investigation of Creep Strain under Permanent Compressive Loading

“…Results of calculation by regressive equations (6), (7), (12), (13), (17), (18) of ultimate (critical) stress cr σ and the initial modulus of elasticity E based on experimental values of stress σ 10 % for specimens tested: during a longterm experiment; stress-free specimens stored during a long-term experiment in the same premises; after removal of compressing stress σ c in 5 years -comply with the requirement of non-contradiction at confidence probability P = 90 % (one-sided criterion), i. e. their discrepancy is random.…”

Flexural behavior of composite structural insulated panels with magnesium oxide board facings

“…The same data for EPS21 Table 4 Material parameter values used in FEA E modulus of elasticity, υ Poisson's ratio, σ pl yield stress, E pl modulus of hardening, β angle of friction, ψ dilation angle, p t0 initial hydrostatic tension strength, ε pl,eq equivalent plastic fracture strain, η stress triaxiality factor, * parameter identification study result and EPS19 were obtained from tests described in EN 826 (uniaxial compression) and EN 1607 (uniaxial tension). In the case of EPS15, these properties were calculated from density-based equations proposed in [38,39]. A literature study was also used to assume Poisson's ratios, υ [40,41], as well as angles of friction, β, and dilation angles, ψ [42,43].…”