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Background Full-field, quantitative visualization techniques, such as digital image correlation (DIC), have unlocked vast opportunities for experimental mechanics. However, DIC has traditionally been a surface measurement technique, and has not been extended to perform measurements on the interior of specimens for dynamic, full-scale laboratory experiments. This limitation restricts the scope of physics which can be investigated through DIC measurements, especially in the context of heterogeneous materials. Objective The focus of this study is to develop a method for performing internal DIC measurements in dynamic experiments. The aim is to demonstrate its feasibility and accuracy across a range of stresses (up to 650 MPa), strain rates ( 10 3 - 10 6 s - 1 ), and high-strain rate loading conditions (e.g., ramped and shock wave loading). Methods Internal DIC is developed based on the concept of applying a speckle pattern at an inner-plane of a transparent specimen. The high-speed imaging configuration is coupled to the traditional dynamic experimental setups, and is focused on the internal speckle pattern. During the experiment, while the sample deforms dynamically, in-plane, two-dimensional deformations are measured via correlation of the internal speckle pattern. In this study, the viability and accuracy of the internal DIC technique is demonstrated for split-Hopkinson (Kolsky) pressure bar (SHPB) and plate impact experiments. Results The internal DIC experimental technique is successfully demonstrated in both the SHPB and plate impact experiments. In the SHPB setting, the accuracy of the technique is excellent throughout the deformation regime, with measurement noise of approximately 0.2 % strain. In the case of plate impact experiments, the technique performs well, with error and measurement noise of 1 % strain. Conclusion The internal DIC technique has been developed and demonstrated to work well for full-scale dynamic high-strain rate and shock laboratory experiments, and the accuracy is quantified. The technique can aid in investigating the physics and mechanics of the dynamic behavior of materials, including local deformation fields around dynamically loaded material heterogeneities.

This study investigated the stress–strain behavior of seamless pipes in the hoop direction using the ring expansion test, which is a non-standardized mechanical testing technique used for evaluating the mechanical properties of round tubes. However, this technique has limitations, such as unidentified specimen geometry, strain measurement, and the estimation of friction coefficients. The study employed experimental, numerical, and analytical methodologies to address these limitations and throughout the study, a novel hoop stress correlation factor (K) was identified to be multiplied by the hoop stress derived equation for reduced section ring specimens. The experimental strain was measured using a newly derived analytical equation, and a mathematical predictive model was developed to estimate the K-factor using the Design of Experiment (DoE) and Design-Expert statistical software. The study concluded that the ring expansion test is a promising technique for evaluating the mechanical properties of seamless pipes similar to the unified axial tensile stress–strain behavior. However, future research is needed to estimate the hoop stress correlation value (K) for all ring geometries. The study's finding of the novel hoop stress correlation factor (K) in the case of a reduced section ring specimen is particularly noteworthy, as it addresses a significant research gap in the field.

Microtexture regions (MTR) are collections of grains with similar crystallographic orientation; their presence in aerospace components can significantly impact component life. Thus, a method to detect and characterize MTR is needed. A potential solution is to use eddy current testing, which is sensitive to local changes in crystallographic orientation, to determine the size and dominant orientation of MTR. In this work, we introduce a technique that combines a variant of the matching component analysis algorithm with level set inversion in order to characterize MTR using eddy current testing data. The method is applied to simulated eddy current testing data of a real titainum specimen. Using this technique, we are able to successfully determine the boundaries and average orientation of MTR in the specimen.

Lead-based water pipelines pose a significant public health risk in the US. The challenge lies in locating these pipelines, as current identification technologies have limitations. This study discusses potential and challenges of identifying the water Service Line (SL) material through a stress wave propagation methodology. Since buried service lines are surrounded by soil and contain water, the stress wave propagation is non trivial. This work presents numerical simulations to investigate the applicability of the proposed method. First, authors consider wave propagation properties that could be used in a stress wave approach to identify buried lead based pipelines. For instance, dispersion curves are quite different for steel, copper, Lead, and PVC pipes filled with water. While the soil surrounding pipes causes a decrease in wave propagation energy due to the energy leakage into the soil medium, this phenomenon can enable the detection of leaked waves with sufficiently sensitive sensors installed near the soil surface. The received signals vary for different types of pipe materials, allowing to differentiate among service line materials. This study’s numerical simulations and lab experiments suggest that stress wave propagation could become a valuable tool for identifying buried lead-based water SL materials.

In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

The impact of pharmaceutical materials properties on drug product quality and manufacturability is well recognised by the industry. An ongoing effort across industry and academia, the Manufacturing Classification System consortium, aims to gather the existing body of knowledge in a common framework to provide guidance on selection of appropriate manufacturing technologies for a given drug and/or guide optimization of the physical properties of the drug to facilitate manufacturing requirements for a given processing route. Simultaneously, material scientists endeavour to develop characterisation methods such as size, shape, surface area, density, flow and compactibility that enable a stronger understanding of materials powder properties. These properties are routinely tested drug product development and advances in instrumentation and computing power have enabled novel characterisation methods which generate larger, more complex data sets leading to a better understanding of the materials. These methods have specific requirements in terms of data management and analysis. An appropriate data management strategy eliminates time-consuming data collation steps and enables access to data collected for multiple methods and materials simultaneously. Methods ideally suited to extract information from large, complex data sets such as multivariate projection methods allow simpler representation of the variability contained within the data and easier interpretation of the key information it contains. In this review, an overview of the current knowledge and challenges introduced by modern pharmaceutical material characterisation methods is provided. Two case studies illustrate how the incorporation of multivariate analysis into the material sciences workflow facilitates a better understanding of materials.

This study aims to explicate the diverse roles of high entropy alloys within nuclear environments. The study extensively investigates the impact of B 4 C on the structural, physical, mechanical, and nuclear shielding properties of synthesized high-entropy alloys (HEAs) comprising FeNiCoCrW, GNP, and B 4 C. The aim is to explore the monotonic effects of B 4 C on the behavioural changes of the HEAs. The present study initially investigates the internal morphology and structural characteristics of the produced composites through the utilization of X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The determination of coefficient of friction values is obtained via wear testing, wherein the values are measured as a function of the sliding distance. The shielding properties of nuclear radiation are determined through the experimental setups for gamma-ray and neutron radiation. The sample encoded as G2, which incorporates both B 4 C and GNPs as reinforcing agents, exhibits the most noteworthy mechanical properties among the samples that were examined. The findings of our study indicate that augmenting the concentration of B 4 C has a significant impact on the efficacy of nuclear radiation shielding. The present study infers that the B 4 C produced within the framework of GNPs plays a significant role in enhancing the overall characteristics of HEAs. This is particularly noteworthy in the context of nuclear applications, where HEAs are being examined as a prospective constituent of forthcoming nuclear reactors. Moreover, B 4 C serves as a versatile instrument in scenarios, where there is a need to enhance mechanical and nuclear shielding properties across a spectrum of radiation energies.

AISI 301 stainless steel samples were annealed over the temperature range of 800–1200°C for 60 minutes to produce different grain sizes. These samples were characterized by ultrasonic immersion technique, tensile test, and optical microscopy. The attenuation of ultrasonic waves measured at a frequency of 20 MHz showed a good correlation with average grain size, hardness, and yield strength of AISI 301 stainless steel samples. A new equation was derived for calculation of yield strength on the basis of ultrasonic wave attenuation and Hall-Petch relation.

Acoustic scattering-based technique is one major approach for characterization purposes and non-destructive testing of structures. This paper investigates the acoustic scattering of a progressive plane wave from two-layered stainless steel/polymer cylindrical shell. The time–frequency techniques are used to study the acoustic scattering from the considered structure. The use of these techniques allows to extract the group velocity and cutoff frequency of circumferential waves. From a temporal signal it is difficult to identify the echoes of different circumferential waves due to the overlapping. To overcome this shortcoming, digital filtering is used to isolate the contribution of each circumferential wave to the total temporal acoustic signal. The time–frequency image of each wave is then constructed using Reassignment Smoothed Pseudo Wigner–Ville (RSPWV) and Reassignment Gabor Transform (RGT). The constructed image can be considered as an acoustic signature of the considered structure. The achieved results show that the time–frequency representation and plane of modal identification can be considered as an alternative of the proper modes theory which is practical in the case of homogeneous structures.

Impedance matching theory is commonly used within the field of microwave absorption theory though extensive research published recently has shed light on the inherent flaws in this well-established theory. Many distinct definitions have been developed for the theory, among them are impedance matching coefficients for interfaces and films. The current study provides compelling evidence that the shortcomings identified within impedance matching theory also extend to these coefficients. These findings underscore that the application of a quarter-wavelength impedance converter in transmission line theory fundamentally departs from the principles underlying quarter-wavelength and impedance matching theories concerned with microwave absorption. The flaws in impedance matching theory are further emphasized in this study.