Papers by Keyword: Non-Destructive

Paper TitlePage

Authors: Camilla Colla
Abstract: The 12th C. Modena Cathedral is a masterpiece testimony of early Romanesque architecture, artand civic values of the time. Following the inclusion in the UNESCO list in 1997, studies, surveysand maintenance works have started. The Emilia’s seismic events of May 2012 have happenedwhen the maintenance operations were already in an advanced phase. The quakes caused damageand re-opening of some historical cracks, in particular in the thin vaults of the naves, near thefaçade and at the junction between naves and choir and crypt. Fragments of brick, mortar from thejoints between bricks and even limited portions of a diagonal rib have fallen to the ground. In viewof seismic assessment and strengthening for improvement of the structural behaviour, detailedstudies of the vaults’ mortar became necessary. The investigation approach was minimal andpreservative, combining on-site close-up visual inspections and micro-destructive testing of themortar joints by mortar penetrometer. For this purpose, openings of 0.25x0.25 m2 in the renderlayer of the 23 vaults were created. The outcome has allowed differentiating between repair mortarsof different strength, used in different historic periods. The mortar resistance was very low butdifferent for lime mortar and gypsum. Values, divided in 3 classes of strength, were found tocorrelate well with the location and severity of the crack pattern and damage map in the vaults. Theresults were useful for a correct design (minimal and reversible) of the cathedral strengtheningintervention.
Authors: Jan Pošta, Jakub Dolejs, Lubomír Vítek
Abstract: Structural timber is a traditional construction material. Timber structures belong to essential parts of almost all historical buildings, especially roof and ceiling structures. Their actual condition affects durability of the whole building, therefore it is necessary to check the conditions of the structure regularly and take care of possible undesirable changes. If these structures have historical value we have to use non-destructive or semi-destructive methods during this investigation. Penetration methods in combination with ultrasonic method are used nowadays [. Penetration devices are suitable to determine the density, surface and internal biological degradation, growth defects and moisture content of the element. The density and the velocity of ultrasonic wave represent input information to derive dynamical modulus of elasticity. Penetration devices work on the principle of measuring the depth of penetration of a steel tip or on the principle of resistance drilling. Another method of determining the density of inbuilt element is the radial core. These methods are semi-destructive. It is the subject matter of the authors research to replace these penetration methods by radiometric measure of mass density. This method is based on the principle of gamma rays dispersion or on the principle of gamma rays absorption in a timber element. Radiometry as a measurement of density is often used for concrete constructions and asphalt pavement now. This measurement can be applied to the inbuilt elements, which is its a main advantage.
Authors: Hai Ning Yang
Abstract: Based on some at present advanced geophysical methods, a non-destructive detection method mainly depending on ground penetrating radar(GPR) has been established by combining with Rayleigh wave method and natural electrical field method. The quality of earth-fill dam not only can be evaluated and analyzed quickly, but also multi-method, multi-parameter, multi-information can be undertaken quantitative analysis through considering geo-technical test and geophysical information. After this method has been successfully applied to Xixia earth-fill dam detection, it is indicated that modern geophysical methods is effective to detect the diseases and faults in dam quality and this method is worthy of popularizing and application in the future.
Authors: Kyung Woo Lee, Kug Hwan Kim, Kwang Ho Kim, Dong Il Kwon
Abstract: The development of the instrumented indentation test (IIT), which gives accurate measurements of the continuous variation in indentation load as a function of depth, has paved the way to assessing tensile properties and residual stress in addition to hardness by analyzing the indentation load-depth curve. In this study, analytic models and procedures are presented for evaluating tensile flow properties and residual stress states using IIT. Tensile properties were obtained by defining representative stress and strain beneath the spherical indenter. The evaluation of residual stress is based on the concepts that the deviatoric stress part of the residual stress affects the indentation load-depth curve, and that analyzing the difference between the residual stressinduced indentation curve and the residual stress-free curve permits evaluation of the quantitative residual stress in a target region.
Authors: Jae Yeol Kim, S.U. Yoon, Kyeung Cheun Jang, Myung Soo Ko, Jae Sin An
Abstract: In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.
Authors: Sean McGuire, Robert Blasi, Ping Wu, Efstathios Loukas, Ejiro Emorhokpor, Svetoslav Dimov, Xue Ping Xu, Jian Qiu Guo, Yu Yang, Balaji Raghothamachar, Michael Dudley
Abstract: We have developed a process that is able to detect, count, and map micropipes on SiC substrates. This process uses a polarized light microscope to scan the wafer. The pictures taken are analyzed with a program that produces a micropipe map as well as numerical defect distribution data in a text file. The results of the process were validated with x-ray topography measurement. The repeatability of this process is also studied and reported.
Authors: Allan Lyckegaard, Henning Friis Poulsen, Wolfgang Ludwig, Richard W. Fonda, Erik M. Lauridsen
Abstract: Within the last decade a number of x-ray diffraction methods have been presented for non-destructive 3D characterization of polycrystalline materials. 3DXRD [1] and Diffraction Contrast Tomography [2,3,4] are examples of such methods providing full spatial and crystallographic information of the individual grains. Both methods rely on specially designed high-resolution near-field detectors for acquire the shape of the illuminated grains, and therefore the spatial resolution is for both methods limited by the resolution of the detector, currently ~2 micrometers. Applying these methods using conventional far-field detectors provides information on centre of mass, crystallographic orientation and stress state of the individual grains [5], at the expense of high spatial resolution. However, far-field detectors have much higher efficiency than near-field detectors, and as such are suitable for dynamic studies requiring high temporal resolution and set-ups involving bulky sample environments (e.g. furnaces, stress-rigs etc.)
Authors: Sheng Chun Li
Abstract: This paper studies the correlation of non-destructive pavement test devices, the falling weight deflectometer (FWD) and Benkelman Beam (BB), in evaluation of pavement structure capacity. Field measurements were made at an expansion highwayG6 in Ningxia Hui Autonomous Region, China. Based on the deflection results measured with FWD and BB, the relationship between FWD and BB was established. The subgrade moduli of the test section were back-calculated. The results show that the ratio of E(sta) and MR(dyn) is consistent with the suggestion of AASHTO 1993. Due to the fact that the use of FWD test is convenient and the results are stable, it demonstrates that the falling weight deflectometer (FWD) is an appropriate device to evaluate the pavement structural and to select the optimal pavement rehabilitation strategy in the near future.
Authors: Seung Hoon Nahm, Jeong Min Kim, Jong Seo Park, Kwang Min Yu, Dong Kyun Kim, Am Kee Kim, Dong Jin Kim
Showing 1 to 10 of 38 Paper Titles