ABSTRACT

In order to capture the effect of joint progressive stiffness degradation with the hardening effect taken into account, the three parametric continuous model is adopted hereafter for the analytical formulation. The current paper is an extension of the previous work (Gizejowski et al. 2012) giving all the details of the developed model together with a calibration procedure for basic model parameters. Experimental data used was obtained from laboratory tests carried out at the Warsaw University of Technology for beam-to-column joints of different reinforcement ratio. The results of calibration exercise as well as the values of calibrated model parameters are given for practical application.

This study focuses on methylol functional benzoxazines as precursors to build a network structure utilizing both benzoxazine and resole chemistry. The first part is a review of systems that contain methylol groups which play a role on their crosslinking formation. The polymerization mechanism and properties of resoles will be highlighted as the most abundant polymers that are characterized by polymerization through condensation reaction of methylol group. In the second part, the effect of incorporating methylol group into benzoxazine monomers is studied. Differential scanning calorimetry (DSC) is used to study the effect of methylol group on the rate of polymerization. Kissinger and Ozawa methods using non-isothermal DSC at different heating rates show that methylol monomer exhibits lower average activation energy compared to the un-functionalized monomer. The effect of adding catalysts into the monomers is …

 Abstract. We investigate harmonic Bergman spaces bp = bp(Ω), 0 < p < ∞, where Ω = Rn \Zn and prove that bq ⊂ bp for n/(k + 1) ≤ q < p < n/k. In the planar case we prove that bp is non empty for all 0 < p < ∞. Further, for each 0 < p < ∞ there is a non-trivial f ∈ bp tending to zero at infinity at any prescribed rate.

Abstract. We prove that ωu(δ) ≤ Cωf(δ), where u: Ω → Rn is the harmonic extension of a continuous map f: ∂Ω → Rn, if u is a K-quasiregular map and Ω is bounded in Rn with C2 boundary. Here C is a constant depending only on n, ωf and K and ωh denotes the modulus of continuity of h. We also prove a version of this result for Λω-extension domains with c-uniformly perfect boundary and quasiconformal mappings.

The aim of this work was to establish the deformation behavior of two vanadium mic-roalloyed medium carbon steels with different contents of carbon and titanium by tensile testing at 77 K. Samples were reheated at 1250 C for 30 min and continuously cooled in still air. Beside acicular ferrite as the dominant morphology in both microstructures, the steel with lower content of carbon and negligible amount of titanium contains consi-derable fraction of grain boundary ferrite and pearlite. It was found that Ti-free steel exhibits a higher strain hardening rate and significantly lower elongation at 77 K than the fully acicular ferrite steel. The difference in tensile behavior at 77 K of the two steels has been associated with the influence of the pearlite, together with higher dislocation density of acicular ferrite.