This paper presents the application of a life fraction hardening rule to the analytical calculation of creep in hot section components. Accurate prediction of creep is critical to assuring the mechanical integrity of heavy-duty, industrial gas turbine (IGT) hardware. The accuracy of such predictions depend upon both the creep models assumed and how those models are implemented in a finite eleme...

In-situ neutron diffraction measurements were performed on monocrystalline samples of the Ni-based superalloy CMSX-4 during N-type g0 raft formation under the tensile creep conditions of 1150 C/ 100 MPa, and subsequently on a rafted sample under the low temperature/high stress creep conditions of 715 C/825 MPa. During 1150 C/100 MPa creep, the g0 volume fraction decreased from ~70% to ~50%, the...

A deformation-mechanism map has been developed for unirradiated zircaloy-4 based on the creep data available from the literature of the last thirty-five years. These data have been analyzed to identify different creep mechanisms, based on the forms of the relationships between stress, temperature and strain rate. This identification allowed the activation energies and other associated creep par...

Internal stress plasticity occurs when a small external stress biases internal mismatch strains produced by, e.g., phase transformation or thermal expansion mismatch. At small applied stresses, this deformation mechanism is characterized by a deformation rate which is proportional to the applied stress and is higher than for conventional creep mechanisms. In this work, we demonstrate the operat...

Aluminum syntactic foams with densities of 1.2–1.5 g/cm3 were deformed at 500 ◦C under constant uniaxial compressive stresses ranging from to 14 MPa. The foam creep behavior is characterized by a short primary stage and a long secondary stage where the strain rate is constant and inimum, followed by a tertiary stage at high stresses. The minimum strain rate varies with stress according to an ap...

The creep and recovery of 5% carboxyl-terminated butadiene acrylonitrile (CTBN) modified epoxy shape memory polymers (SMP) was studied. The results were compared with those for the unmodified epoxy SMP. The glass transition temperatures (Tg) were determined using Advanced Rheometric Expansion System (ARES). The creep behavior of the unmodified epoxy and 5wt.% CTBN modified epoxy SMP were studie...

In vivo measurements of the viscoelastic properties of breast tissue are described. Ultrasonic echo frames were recorded from volunteers at 5 fps while applying a uniaxial compressive force (1-20 N) within a 1 s ramp time and holding the force constant for up to 200 s. A time series of strain images was formed from the echo data, spatially averaged viscous creep curves were computed, and viscoe...

Accumulation of fatigue microdamage in cortical bone specimens is commonly measured by a modulus or stiffness degradation after normalizing tissue heterogeneity by the initial modulus or stiffness of each specimen measured during a preloading step. In the first experiment, the initial specimen modulus defined using linear elastic beam theory (LEBT) was shown to be nonlinearly dependent on the p...