Digital image correlation (DIC) is widely used as a tool to measure displacements and surface strains. The generation of speckle pattern in DIC technique has some limitations. In addition to spray paint, other techniques including laser speckle have also been proposed to generate speckle patterns. In previous studies, the use of DIC as a Non-destructive technique has been limited to detect the surface cracks. In the current study, the feasibility of DIC for detection of subsurface defects was investigated. A laser beam was utilized to generate the DIC speckle pattern. The tensile load was applied to a polypropylene specimen containing an artificial subsurface defect. The DIC images were recorded and analyzed before and after loading the specimen. The results of surface displacement in the direction of tension and perpendicular to tension revealed the defect. To study further, the surface strains of the specimen were determined. In the obtained results, the strain concentration indicated the defect in the specimen. The approximate size and shape of the artificial defect are recognizable in the measured strain distribution.

In this research, the possibility of evaluating Non-destructive materials using terahertz waves was investigated. For this purpose, the results of determining the specific defects dimensions on the samples of aluminum, plexiglas and ceramic zirconium dioxide with the results of dimensional measurements with methods such as Coordinate Measuring Machine (CMM), micro-X and Visual Measurement Machine (VMM) was compared. In order to conduct research, depending on the nature of the sample and the required information, two configurations (transmission and reflection) of the terahertz imaging system based on the terahertz time domain spectroscopy system were used in which the generation and detection of terahertz waves pulses were performed using a femto-second laser. The results showed that Non-destructive terahertz test was used to identify defects (very shallow surface defects and hidden defects in sample tissue) and measurements were superior to some of the common methods. In the final, the terahertz wave imaging method is a Non-destructive test that can compete with conventional methods.

In this paper, Digital Image Correlation method (DIC) and the introduction of a new Nondestructive method for measuring residual stresses in mechanical parts has been investigated. In this regard, with the purpose of scientific proof of the proposed new method, a review of the related work to the presented idea and its details has been discussed. Initially, the principles of digital image correlation method and the methods used to calculate correlation coefficients are presented. In order to evaluate the accuracy of digital image correlation method outputs, by construction the required equipment and doing experimental tests, comparing the output results of the digital image correlation method and the simulation results of finite element are discussed. In the following, the proposed method for measuring the residual stresses in mechanical parts by applying loads in the elastic and Nondestructive area has been discussed. The proposed relationship, which is based on Hooke's law, is capable of evaluating and calculating residual stresses in a Nondestructive, full-screen, and high-precision manner. For scientific proof, the steel samples are welded by the SMAW process and the amount of residual stresses found in the parts has been calculated.

Today, nondestructive methods are widely used to determine the quality of agricultural products. Meanwhile, visible and near-infrared (Vis/NIR) spectroscopy is regarded as one of the most widely used methods in the field of quality assessment of agricultural products. In this study, a system was developed to measure the Vis/NIR spectra of tomato fruit samples in the half-transmittance mode of measurement. Halogen lamps were used as the sources of irradiation and a portable fiber optic spectrometer was utilized to collect the spectra in the range of 400-100 nm. Immediately after collecting the spectra of 170 tomato samples, harvested at different stages of ripening, the firmness of the samples was measured using the standard Magness-Taylor penetration test. In order to eliminate the effects of irregular factors, different preprocessing methods were applied to the collected spectra. Then, partial least squares (PLS) regression was implemented to develop the firmness predictive models. Preliminary results showed two absorption peaks around 670 and 990 nm in the acquired spectra that were related to the chlorophyll and water contents of tomato, respectively. The spectroscopy method could nondestructively predict the tomato fruit firmness with a correlation coefficient (rp) of 0. 920 and the root mean squares error of prediction (RMSEP) of 2. 5 nm.

Most of structural destructions take place because of components fracture. This event occurred by cracks that their development is considered as a serious threat for the treatment of structure. Therefore the exhibition and distinction methods of crack were the subject of wide verifications during last decade. Considering the local hardness differences arising from cracking and its effect on the treatment of structure, this article studies the distinction of internal crack in cantilever beam. Specimens were placed on harn10nic analyses and the base of recorded reaction was analyzed by Wavelet transform. Also this text offers the sensitiveness of the above method due to the depth. angle and situation of crack, and possibility of its identification, in various conditions.

In this paper, the capabilities of displacement curvature derived from static response data for finding the location and severity of damage in Euler-Bernoulli beams are assessed.Static response of a beam is obtained using the finite element modeling. In order to reduce the number of measured nodal displacements, the beam deflection is fitted through a polynomial function using a limited number of nodal displacements. An indicator based on displacement curvature obtained for healthy and damaged structure is utilized to identify the damage. The influence of many parameters may affect the efficiency of the method such as the number of elements, the value and location of applied load as well as noise effect is investigated. Two test examples including a simply supported and a cantilever beam are considered.Numerical results show that using the method, the locations of single and multiple damage cases having different characteristics can be well determined.