Experimental and numerical investigation of the asymmetric primary creep of a fibre reinforced refractory concrete at 1200 °C

Abstract

Tension/compression asymmetry is a key feature of the creep behaviour of ceramics at high temperature. This paper investigates the capability of Drucker-Prager creep model, based on a sensitivity of the equivalent creep stress to the pressure, to account for the creep behaviour of a refractory concrete subjected to compression and bending. A relevant calibration procedure is proposed. The analysis mainly focuses on the associativity of the creep flow. A profile analysis of a compressed sample allows concluding that the creep flow is dilatant and thus associated. A discussion on the neutral axis shift during bending creep is carried out with the model calibrated on the experiments.

New advances in the laboratory characterization of refractories: testing and modelling

“…Modelling the in-use behaviour of refractory structures requires a suitable model that is able to describe the asymmetric creep as evidenced by the experiment [11,14,17]. In the case of refractory concrete, the variability inherent to the material necessitates to identify the parameters of the models for many samples and several processing and testing conditions.…”

“…The material is an ultra-low cement bauxite matrix that is reinforced with bauxite aggregates and 2 wt.% of FeCrAl fibres. It is described in [17,18].…”

“…m defines the intensity of the hardening, n is the stress exponent, A is a multiplicative constant, b controls the effect of p on the creep intensity, and c defines how the creep affects the spherical and deviatoric components of the strain increment. The identification procedure, detailed in [17], assumes that eccentricity is very low, which means that the pseudopotential is almost linear, except for a very low deviatoric stress. Assuming a value of the dilation angle, this calibration method allows identification of the values of parameters A, m, n and b from only few compression tests and one bending test coupled with a kinematic full-field measurement.…”

“…A finite element simulation of this test allows computation of the neutral axis location as a function of parameter b. It has been proven [17] that the value of A does not affect this result. For a given assumption about dilation angle the value of b is thus identified to match the experimental neutral axis location.…”

Compressive Creep Measurements of Fired Magnesia Bricks at Elevated Temperatures Including Creep Law Parameter Identification and Evaluation by Finite Element Analysis

“…The Norton-Bailey creep law can be used to describe the behavior in all three creep stages, it is a differential approach which includes the stress dependency on the creep behavior and it can be implemented in finite element programs for the simulation of transient stress states in refractories [13]. The applicability of the Norton-Bailey creep equation to characterize the creep behavior of refractories has been proven by previous studies [10,11,14].…”