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•Defects incurred at various levels of FRP bonded reinforced concrete (FRPRC) structures have been discussed.•Shortcomings of other non-destructive evaluation techniques on FRPRC ...strcutures are highlighted.•Recent advances in active infrared thermography (IRT) and post-processing techniques have been discussed.•A critical review conducted on the application of active IRT for inspection of FRPRC structures.•Recommendations delivered to further enhance IRT applications for inspection of FRPRC structures.
Fiber reinforced polymer (FRP) composites have become one of the most important strengthening and retrofitting materials for reinforced concrete structures. However, these external reinforcements are prone to debond due to improper installation or in-service damage. This leads to deterioration of the overall strength and integrity of the composites; hence its early detection and characterization are inevitable. Infrared thermography (IRT) is a fast-imaging technique that could identify and characterize surface and near-surface defects. The success of IRT for qualitative and quantitative investigations of defects in FRP concrete interface is due to the development of new thermography and post-processing techniques. These developments have enabled fast and accurate characterization of defects at a much lower computational cost. This review covers discussion on the incurrence of defects in FRP bonded to concrete, thermography techniques, post-processing algorithms, and limitation of other non-destructive evaluation techniques. There has been extensive research attempting to characterize flaws of different features using sophisticated thermography techniques especially on FRP bonded concrete, however the inclination towards exploration of novel post-processing techniques is at its primitive. A in-depth understanding of the applicability of different post-processing techniques can not only enhances the quality of thermal image but also deter employment of sophisticated thermography technique. For instance, realization of principal component analysis (PCA) has allowed improved thermal image free of non-uniform thermal distribution even with prolonged heating of FRP surface using simple and low-cost halogen lamp. Likewise, the advancement is thermography technique such as laser thermography has enabled imaging of far FRP defects without aid of convoluted post-processing techniques. This review also covers the additional advantage that combination of thermography and post-processing techniques offers in terms of producing an even more improved image. Moreover, the recommendations for future research are presented for the improvements of defect detections, especially for near-surface defects in FRP strengthened concrete structures.
We examine numerically the feasibility of using a relatively new solitary wave-based non-destructive test (NDT) method for site-specific bone quality assessment. Towards this end, we present ...numerical predictions of the effective elastic modulus of trabecular bone in the proximal femur using highly nonlinear solitary waves (HNSWs) propagating in a one-dimensional chain of spherical steel particles. A computational bone reconstruction technique, enabled through topology optimization, is developed to generate high-resolution finite-element models representing the complex architecture of the trabecular network in the femoral neck region of the proximal femur. The reconstructed bone microstructure models are then used as the inspection medium in a virtual NDT setup in the form of a hybrid discrete-element/finite-element (DE/FE) model, capable of simulating the propagation of HNSWs in the granular chain and their interaction with the bone microstructures. By inserting a face sheet between the granular chain and the porous trabecular bone model, our calculations evince that dynamic loading by the incident solitary wave results in nearly uniaxial deformation of the bone microstructure (rather than localized contact indentations), and this is shown to enhance the accuracy and reliability of the solitary wave-based prediction of the bone’s effective elastic modulus. Using the delay of the primary reflected solitary wave in the estimation of the elastic modulus of bone, we are able to estimate the effective elastic moduli of the porous bone models with adequate accuracy. Based on these numerical findings, we believe that solitary wave-based non-destructive evaluation of computationally reconstructed artificial bone models could form the baseline for advanced bone quality assessment tools.
•We examined the feasibility of using a solitary wave-based NDT technique for bone quality assessment.•A hybrid DE/FE model was developed to study the solitary wave interaction with trabecular bone in the proximal femur.•A bone microstructure reconstruction scheme based on topology optimization was used to generate the bone models.•Inserting a face sheet between the granular chain and the bone resulted in more accurate estimates of the bone’s modulus.•The proposed technique can capture site-specific differences in the modulus of trabecular bone in the proximal femur.
Additive manufacturing is based on high-precision material deposition to build a final part or component by using various techniques. It is being one of the main advances in the fourth industrial ...revolution. This type of manufacturing is not new, although it is growing. There are many types of additive manufacturing techniques, and the use of efficient inspection methods to ensure a certain level of quality, and to detect faults, porosities, etc., are required in the industry. Nondestructive Testing is widely applied, and particularly in additive manufacturing, to ensure efficient quality control and preventive/predictive maintenance without changing the characteristics and initial state of the material. Each Nondestructive Testing technique is based on different physical principles; therefore, the selection and correct use of each technique depends on the application, the manufacturing process, the type of material and the possible discontinuities, among many others. This article develops a complete, exhaustive, and updated review and analysis of the state of the art of Nondestructive Testing applied in additive manufacturing. The main characteristics of the processes are analyzed, highlighting the most relevant works and the challenges that each technique should face. An analysis of techniques necessary for the development of Nondestructive Evaluation has been carried out, mainly Machine Learning techniques used for the quantification, detection and analysis of defects detected by Nondestructive Testing techniques.
•An exhaustive and updated review of the state of the art of Nondestructive Testing applied in additive manufacturing.•The main characteristics of the processes are analyzed, showing the most relevant works and challenges for each technique.•An analysis of techniques necessary for the development of Nondestructive Evaluation has been carried out.•Machine Learning techniques are used for the analysis of defects detected by Nondestructive Testing techniques.
The escalating usage of paper cups and packaging materials with plastic coatings has evolved into a substantial environmental and health concern, evidenced by the report of microplastics in human ...blood. This research introduces an innovative laser-assisted thermal lens (TL) technique for the precise detection and measurement of microplastics, specifically those leaching from the inner plastic coatings of paper cups. Employing a multipronged approach encompassing scanning electron microscopy, optical microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, UV–visible, and Raman spectroscopy, a comprehensive investigation is conducted into the leaching of microplastics into hot water from paper cups. The thermal diffusivity (D) of water samples containing microplastics is determined using the TL technique based on 120 observations for each temperature conducted using paper cups from three distinct manufacturers. The observation of a strong correlation between the number of microplastic particles (N) and D of the water sample enabled the setting of a linear empirical relation that can be used for computing the microplastics in water at a particular temperature. The study thus proposes a surrogate method for quantifying microplastics in water using the sensitive and non-destructive TL technique.
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•First report of thermal lens-based detection and quantification of microplastics.•Microplastic concentration increases with water temperature, reaching 109.4 × 106/l.•Greater the microplastics, greater the thermal diffusivity.
The surface temperature of a drying wooden board is strongly related to the drying process. However, it is relatively difficult to determine the surface temperature accurately during drying. In this ...paper, an experimental setup for analyzing the wood surface during drying by thermal imaging as well as dry and wet-bulb temperature reference surfaces was tested. Spruce sapwood samples were dried in various climates and evaluated with respect to both mass loss and surface temperature. The experimental setup enabled both qualitative and quantitative analysis of the wood drying process. The results showed that thermal imaging enabled a detailed view of the drying progression. The distinct correlation between surface temperature and mass change showed that an accurate determination of a basic, often considered, and difficult-to-determine drying potential is possible.
•Implementation of Acoustic Emission (AE) to understand source and location of crack.•Use of NDT techniques like DCPD and DIC to assist in interpreting AE.•The AE, DCPD and DIC techniques showed good ...correlation for detecting the damage.•Relatively accurate location of the AE events using times of arrival data.•The waveform and frequency analysis of the AE events aided in discerning at least the two distinct types of crack present.
Optimizing acoustic emission (AE) is useful to understand fatigue crack growth of metal structures. Experimental investigation of fatigue in steel with an edge notch was performed using AE to understand source and location of crack formation and growth. Non-Destructive Techniques like Direct Current Potential Drop (DCPD) and Digital Image Correlation (DIC) are useful in assisting to interpret the AE. The cumulation of AE correlated well with the initiation and propagation similar to potential drop values and DIC strain field. 2D AE source location technique was successfully implemented to monitor crack growth. Frequency content correlate with the mode of crack growth.
This paper reviews recent advances in sensor technologies for non-destructive testing (NDT) and structural health monitoring (SHM) of civil structures. The article is motivated by the rapid ...developments in sensor technologies and data analytics leading to ever-advancing systems for assessing and monitoring structures. Conventional and advanced sensor technologies are systematically reviewed and evaluated in the context of providing input parameters for NDT and SHM systems and for their suitability to determine the health state of structures. The presented sensing technologies and monitoring systems are selected based on their capabilities, reliability, maturity, affordability, popularity, ease of use, resilience, and innovation. A significant focus is placed on evaluating the selected technologies and associated data analytics, highlighting limitations, advantages, and disadvantages. The paper presents sensing techniques such as fiber optics, laser vibrometry, acoustic emission, ultrasonics, thermography, drones, microelectromechanical systems (MEMS), magnetostrictive sensors, and next-generation technologies.
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