The Experts below are selected from a list of 48792 Experts worldwide ranked by ideXlab platform

Ton Peijs - One of the best experts on this subject based on the ideXlab platform.

  • strain sensing behaviour of elastomeric composite films containing carbon nanotubes under cyclic Loading
    Composites Science and Technology, 2013
    Co-Authors: Rui Zhang, Renata Valenca, Emiliano Bilotti, Qiang Fu, Ton Peijs, Hua Deng
    Abstract:

    Abstract The resistivity response under cyclic Loading of thermoplastic polyurethane (TPU) multi-walled carbon nanotube (MWNT) elastomeric nanocomposite films fabricated by a solution process with good nanotube dispersion and low percolation threshold ( p c  ∼ 0.35 wt.%) is reported. At a strain amplitude of 5%, the strain-dependent resistance shows good recoverability and reproducibility after stabilisation by cyclic Loading. When larger strains are applied, only a small part of the resistance is recoverable, and a double peak appears when a single Loading Cycle is applied. This behaviour is attributed to the competition of network deformation and network reformation during cyclic Loading of the polymer composites.

  • carbon nanotube polymer coatings for textile yarns with good strain sensing capability
    Sensors and Actuators A-physical, 2012
    Co-Authors: Rui Zhang, Renata Valenca, Emiliano Bilotti, Qiang Fu, Ton Peijs, Hua Deng
    Abstract:

    Abstract In this study, a commercially available Spandex multifilament yarn was coated with a thermoplastic polyurethane/carbon nanotube (TPU/CNT) conductive polymer composite (CPC), and conductive elastic yarns with good strain sensing ability were achieved with equivalent CNT concentrations as low as 0.015 wt.%. The resistance per meter coated yarn decreased with increasing CNT concentration in the CPC coating, while in the case of a homogeneous coating, the CPC concentration in the coating solution did not have a significant effect on the resistance per meter coated yarn. Upon cyclic Loading, the strain sensing behaviour showed partial recovery of resistance in the first Loading Cycle, while good reversibility was observed a number of Cycles, giving these materials good potential as sensors for smart textiles.

Rui Zhang - One of the best experts on this subject based on the ideXlab platform.

  • strain sensing behaviour of elastomeric composite films containing carbon nanotubes under cyclic Loading
    Composites Science and Technology, 2013
    Co-Authors: Rui Zhang, Renata Valenca, Emiliano Bilotti, Qiang Fu, Ton Peijs, Hua Deng
    Abstract:

    Abstract The resistivity response under cyclic Loading of thermoplastic polyurethane (TPU) multi-walled carbon nanotube (MWNT) elastomeric nanocomposite films fabricated by a solution process with good nanotube dispersion and low percolation threshold ( p c  ∼ 0.35 wt.%) is reported. At a strain amplitude of 5%, the strain-dependent resistance shows good recoverability and reproducibility after stabilisation by cyclic Loading. When larger strains are applied, only a small part of the resistance is recoverable, and a double peak appears when a single Loading Cycle is applied. This behaviour is attributed to the competition of network deformation and network reformation during cyclic Loading of the polymer composites.

  • carbon nanotube polymer coatings for textile yarns with good strain sensing capability
    Sensors and Actuators A-physical, 2012
    Co-Authors: Rui Zhang, Renata Valenca, Emiliano Bilotti, Qiang Fu, Ton Peijs, Hua Deng
    Abstract:

    Abstract In this study, a commercially available Spandex multifilament yarn was coated with a thermoplastic polyurethane/carbon nanotube (TPU/CNT) conductive polymer composite (CPC), and conductive elastic yarns with good strain sensing ability were achieved with equivalent CNT concentrations as low as 0.015 wt.%. The resistance per meter coated yarn decreased with increasing CNT concentration in the CPC coating, while in the case of a homogeneous coating, the CPC concentration in the coating solution did not have a significant effect on the resistance per meter coated yarn. Upon cyclic Loading, the strain sensing behaviour showed partial recovery of resistance in the first Loading Cycle, while good reversibility was observed a number of Cycles, giving these materials good potential as sensors for smart textiles.

M. Freitas - One of the best experts on this subject based on the ideXlab platform.

  • New Cycle counting method for multiaxial fatigue
    International Journal of Fatigue, 2014
    Co-Authors: V. Anes, L. Reis, Bin Li, M. Freitas
    Abstract:

    Abstract Multiaxial fatigue is a very important physical phenomenon in several mechanical components. Fatigue life study under cyclic stresses is of utmost importance to avoid unexpected failure of equipments, vehicles or structures. Among several fatigue characterization tools, a correct definition of a Loading Cycle under multiaxial fatigue Loading conditions shows to be crucial to estimate multiaxial fatigue life. The aim of this work is to achieve a correct definition for a multiaxial fatigue Loading Cycle and accomplish a multiaxial fatigue model to estimate block’s fatigue life under multiaxial Loading conditions. To reach this goal, several Loading paths were carried out using the 42CrMo4 low alloy steel under different Loading conditions. Sequential, proportional, non-proportional and asynchronous Loading effects were modulated through eleven Loading blocks. Furthermore, two models were proposed: a Cycle counting method and a fatigue life evaluation criterion. The results from the proposed models were correlated with the fatigue data and compared with two well known Cycle counting models: the Bannantine and Socie and the Wang and Brown criteria. The proposed models were successfully validated by experimental data. Results show that the new proposals lead to an improved multiaxial fatigue characterization under complex Loading conditions.

  • comparative study on biaxial low Cycle fatigue behaviour of three structural steels
    Fatigue & Fracture of Engineering Materials & Structures, 2006
    Co-Authors: M. Freitas, L. Reis
    Abstract:

    In this study the uniaxial/biaxial low-Cycle fatigue behaviour of three structural steels (Ck45 normalized steel, 42CrMo4 quenched and tempered steel and AISI 303 stainless steel) are studied, evaluated and compared. Two parameters are considered for estimating non-proportional fatigue lives: the coefficient of additional hardening and the factor of non-proportionality. A series of tests of uniaxial/biaxial low-Cycle fatigue composed of tension/compression with cyclic torsion were carried out on a biaxial servo-hydraulic testing machine. Several Loading paths were carried out, including proportional and non-proportional ones, in order to verify the additional hardening caused by different Loading paths. The experiments showed that the three materials studied have very different additional hardening behaviour. Generally, the transient process from the initial Loading Cycle to stabilized Loading Cycle occurs in a few Cycles. The stabilized cyclic stress/strain parameters are controlling parameters for fatigue damage. A factor of non-proportionality of the Loading paths is evaluated based on the Minimum Circumscribed Ellipse approach. It is shown that the microstructure has a great influence on the additional hardening and the hardening effect is dependent on the Loading path and also the intensity of the Loading.

Karen Margaret Holford - One of the best experts on this subject based on the ideXlab platform.

  • damage classification in reinforced concrete beam by acoustic emission signal analysis
    Construction and Building Materials, 2013
    Co-Authors: Shahiron Shahidan, Rhys Pulin, Norazura Muhamad Bunnori, Karen Margaret Holford
    Abstract:

    Acoustic Emission (AE) is a non-destructive testing technique which can be used to identify both the damage level and the nature of that damage such as tensile cracks and shear movements at critical zones within a structure. In this work, the acoustic emission parameters of amplitude, rise time, average frequency and signal strength were used to classify the damage and to determine the damage level. Laboratory experiments were performed on a beam (150 × 250 × 1900 mm). The acoustic emission analysis was successfully used to determine crack movements and classify damage levels in accordance with the observations made during an increasing Loading Cycle.

D D L Chung - One of the best experts on this subject based on the ideXlab platform.

  • damage in carbon fiber reinforced concrete monitored by electrical resistance measurement
    Cement and Concrete Research, 2000
    Co-Authors: Dragosmarian Bontea, D D L Chung
    Abstract:

    Damage of carbon fiber-reinforced concrete was revealed by an increase in the DC electrical resistance in the stress direction during dynamic compression. Minor damage that did not involve a change in modulus resulted in a partially reversible increase in resistance during Loading at a stress above that in prior Loading. Major damage that involved a decrease in modulus resulted in resistance increase occurring in every Loading Cycle irrespective of prior Loading and in an irreversible increase in the baseline resistance.