The Experts below are selected from a list of 95019 Experts worldwide ranked by ideXlab platform

Ji Wooseok - One of the best experts on this subject based on the ideXlab platform.

  • Complementary ex Situ investigations of various fracture modes in a single-edge-notched symmetric cross-ply laminate subjected to tensile loading
    Elsevier, 2020
    Co-Authors: Hong Chaeyoung, Ji Wooseok
    Abstract:

    In Situ experimentation using synchrotron radiation computed tomography (SRCT) is instrumental to observe subsurface mechanical behavior of composite materials in real time. However, the investigation areas of SRCT are often limited by its experimental configurations. In the present study, an ex Situ observation is carried out to compliment the in Situ Test results reported previously in the literature. Previous SRCT-based in Situ experiment on the single-edge-notched symmetric cross-ply laminate has visualized various failure modes at the notch, which are sequentially occurring inside the specimen. The Tested specimen is further examined here using a laboratory-scale X-ray CT device with a dye penetrant. Delamination failures interacting with longitudinal and transverse cracks, which are not detected by the in Situ Test, are found with other failure modes distributed over the entire specimen area. The ex Situ and in Situ experimental results are complementary and both of them are required to comprehensively understand the various and complex failure mechanisms of the composites

Chaeyoung Hong - One of the best experts on this subject based on the ideXlab platform.

  • complementary ex Situ investigations of various fracture modes in a single edge notched symmetric cross ply laminate subjected to tensile loading
    Composites Communications, 2020
    Co-Authors: Chaeyoung Hong
    Abstract:

    Abstract In Situ experimentation using synchrotron radiation computed tomography (SRCT) is instrumental to observe subsurface mechanical behavior of composite materials in real time. However, the investigation areas of SRCT are often limited by its experimental configurations. In the present study, an ex Situ observation is carried out to complement the in Situ Test results reported previously in the literature. Previous SRCT-based in Situ experiment on the single-edge-notched symmetric cross-ply laminate has visualized various failure modes at the notch, which are sequentially occurring inside the specimen. The Tested specimen is further examined here using a laboratory-scale X-ray CT device with a dye penetrant. Delamination failures interacting with longitudinal and transverse cracks, which have not been detected by the in Situ Test, are found with other failure modes distributed over the entire specimen area. The ex Situ and in Situ experimental results are complementary and both of them are required to comprehensively understand the various and complex failure mechanisms of the composite.

Adrian Long - One of the best experts on this subject based on the ideXlab platform.

  • development of a new in Situ Test method to measure the air permeability of high performance concretes
    Ndt & E International, 2014
    Co-Authors: Kai Yang, P A M Basheer, Y Bai, Bryan Magee, Adrian Long
    Abstract:

    Although several in Situ techniques, including the Autoclam Permeability System, are available to examine normal concretes (NCs) for this purpose, none are sufficiently sensitive to quantify and distinguish relative high performance concrete (HPC) performance. Therefore, to assess the HPC performance characteristics using the Autoclam air permeability Test methodology, two key modifications were investigated and a new Test protocol developed. The first modification considered a reduced volume of compressed air applied to the Test area (named LV Test), and the second an increased Test area (named A-75). The reliability of the proposed modifications was investigated by comparing against a laboratory-based gas permeability Test method (RILEM air permeability Test). Surface resistivity and relative humidity were assessed to evaluate the influence of moisture conditions on in Situ air permeability Test results. A strong correlation between LV Test and RILEM air permeability Test results was found when the free moisture near concrete surface regions (up to 20 mm) was removed. It was concluded that the LV Test exhibits strong potential to become an established method for assessing in Situ HPC permeability.

Salam Alsabah - One of the best experts on this subject based on the ideXlab platform.

  • the post installed screw pull out Test development of a method for assessing in Situ concrete compressive strength
    Journal of building engineering, 2021
    Co-Authors: Salam Alsabah, Shah Nur Alam Sourav, Ciaran Mcnally
    Abstract:

    Abstract In concrete structures, the current methodology for concrete strength estimation combines the use of in-Situ Test methods with destructive techniques (taking cores). In-Situ Tests are indirect approaches, and can be affected by several uncontrolled factors, thus inducing uncertainty in the strength estimate. Low cost in-Situ methods are often deployed in practice, without taking due consideration of the low reliability. Thus, the reliability of the estimated concrete strength is always a questionable issue. In this context, this paper seeks to develop an in-Situ Test method as an alternative to the available techniques to assess in-Situ compressive strength of concrete. The PSP Test is proposed based on the modified pullout Testing of post-installed screw. The Test is a partially destructive technique that involves insertion of an oversized screw into a predrilled hole in the hardened concrete and subsequent pullout of the screw compelling the concrete to follow a specific failure pattern – a complete pullout failure. The peak load obtained in the process is then correlated to the concrete compressive strength. In determining an appropriate and robust configuration for the PSP Test, commercially available screws of different sizes were investigated along with different sizes of drilled hole. High strength correlation of the PSP Test in mortar with selected Test configuration reveals the potential of the Test to be used in the strength assessment. Further investigations are proposed to confirm the suitability of the Test to be applied in concrete.

Koji Nakagawa - One of the best experts on this subject based on the ideXlab platform.

  • a quality control method for shotcrete strength by pneumatic pin penetration Test
    Ndt & E International, 2001
    Co-Authors: Keisuke Iwaki, Akinobu Hirama, Shinobu Kaise, Koji Mitani, Koji Nakagawa
    Abstract:

    Shotcrete is applied as a significant support element in tunneling because of its rapid strength development by adding accelerators. Thus the investigation of real shotcrete strength of tunnel lining is required for stabilization of excavation surfaces. Therefore, a pin penetration Test using air pressure as the penetrating energy is proposed as a simple in Situ Test method. In this method, the penetration depth is used as an indication. Because of the close relationships between the penetration depth and wide range of compressive strength obtained from laboratory and field Tests, the new Testing method is considered effective for shotcrete. In addition, the application of this simple in Situ Test enables strength control to be undertaken with short intervals and to identify nonuniformity of the lining caused by accelerator dosage.