The present paper will describe an approach for the simultaneous real-time compensation of hysteresis, creep and force-dependence effects of a piezoelectric stack actuator by a feed-forward controller. The basis of the feed-forward controller is given by so-called complex creep and hysteresis operators, which when adequately implemented, lead to a precise model of the creep and hysteresis chara...

Coal pillars from old mines undergo creep, a type of time?dependent deformation. Research on underground engineering stability coal has increasingly focused long?term strength as an important mechanical index the creep characteristics pillars. This study performed conventional triaxial compression and tests anthracite under different confining pressures. The law was studied according to test re...

This work focuses on time-dependent rheological behaviour of bacterial cellulose (BC) hydrogel. Due to its ideal biocompatibility, BC hydrogel could be employed in biomedical applications. Considering the complexity of loading conditions in human body environment, time-dependent behaviour under relevant conditions should be understood. BC specimens are produced by Gluconacetobacter xylinus ATCC...

ÐThe longitudinal primary creep of long-®ber composites is modeled by considering the transient stress states arising from load transfer from the weaker matrix phase to the stronger ®ber phase as the composite transitions from the elastic state present immediately after loading to steady-state stage where both phases creep. The e€ect of primary creep of each of the phases on the primary creep o...

Ligaments, tendons and other soft tissues are nonlinearly viscoelastic. To discriminate among various constitutive equations which may be used to describe the tissue, appropriate experimental modalities are requisite. Ideally, testing should span physiologic ranges for load (or strain), load history (recovery and reloading), and load onset and duration, and a robust model will fit all data. Met...

pavement permanent deformations due to lack of shear strength in mixture are a major reason of rutting. any simple test to determine mixtures resistance to permanent deformation isn’t distinguished in the 1st level of superpave mix design method and prevalent methods for evaluating mixture rut resistance are expensive and time-consuming. two aggregate types, gradations, asphalt cements and fill...

By using of combining theoretical model with empirical model, the nonlinear viscoelastic-plastic constitutive equations of soybean and cottonseed were developed on the basis of the creep test. The parameter inverse problem of constitutive model was proposed using improved particles swarm optimization. Numerical simulations of creep of soybean and cottonseed were carried out. The definition of c...

The creep and stress relaxation behaviors of coal are common in mining. unified constitutive model is suitable to describe predict both the evolution characteristics rocks. generalized Kelvin core element for traditional improved component models reflect nonlinear relaxation. In this paper, an damage model, which could relation evolution, was established based on a comparison models, responding...