Common Test Methods Research Articles

Void distribution in a brazed cemented carbide steel joint analyzed by X-ray microscopy

Brazing is a relatively fast process that offers sufficient strength in the joint of dissimilar materials. Cemented carbides are often brazed onto steel components in order to improve the wear resistance of engineering tools. In the case of brazing such materials in an ambient atmosphere, a flux is necessary to improve the wetting of the liquid filler alloy on the surfaces. In some cases, the flux cannot be sufficiently removed from the small joint, thus forming voids during solidification. This phenomenon can greatly affect the integrity of the joint. Such voids are not adequately detectable by visual inspection or common nondestructive testing methods, such as ultrasonic scanning, acoustic emission testing, or thermography. In this study, X-ray microscopy is shown to provide adequate visualization and a quantitative analysis of the dispersion of voids within brazed components of cold work steel, 115CrV3, and cemented carbide, K10 (ISO 513). One of the challenging tasks when analyzing the aforementioned brazed materials is achieving a sufficiently high resolution within the joint gap, since the sample materials have similar X-ray absorption coefficients. Such high resolution was successfully achieved in this study by means of multiple scanning and image reconstruction techniques, such as beam filtering, dataset levelling, and noise removal. The voids on the 115CrV3-side are found to expand radially towards the edges of the specimen up to a maximum volume of 1.18E + 07 µm3. The same radial pattern was detected on the side of the K10, where the voids contracted in volume towards the center of the specimen. However, the K10-side was found to exhibit relatively larger voids with a maximum volume of 7.70E + 07 µm3, that is approximately seven times larger than that detected on the 115CrV3-side.

Direct shear test for the assessment of rheological parameters of concrete for 3D printing applications

Rheology of concrete plays a major role in concrete 3D printing applications, where the concrete is pumped at high pressure and extruded through a nozzle at low speed to build the structural component. The 3D printable concrete should be stiff and is different to normal or self-compacting concrete. Hence, the common testing methods used to estimate the rheological parameters are not suitable for 3D printable concrete. In this study, the direct shear test is trialled as a potential method to measure the rheological parameters of different mixes of concrete. The effects of water–cement ratio and shear rates on rheological parameters were examined. The tests were carried out with varying shear rates, ranging from 0.5 to 15 min−1, and normal stresses, ranging from 2 to 15 kPa, for mixes with water–cement ratios of 0.3, 0.4 and 0.6. Further testing was carried out on mixes with varying aggregate to cement and fine to total aggregates ratios to study the effect of binder and aggregate proportions on the rheology of mortar. It was found that the shear rates, 0.5 to 15 min−1, have little effect on the cohesion values and friction angles. Further, the behaviour of the mixes was found to be following the Mohr–Coulomb model.

Correlation between the performance of solid masonry prisms and wallettes under compression

Strength and deformation characteristics of masonry under uniaxial compression are researched over decades using prisms and wallettes; however, correlation between these two common test methods is not firmly established. Masonry design standards provide expressions and tabulated data for the determination of the compression characteristics from either the prism or the wallette tests. Subsequently researchers compared the standards and made conclusions on their respective conservativism or otherwise, without any regard to the way these provisions have been developed for these design standards. Hence an attempt was made to correlate the behaviour of the solid masonry prism to the wallette compressive behaviour. Fifty prisms and forty wallettes were constructed and tested using five different types of units and two mortar mixes. The test results have revealed that the prism tests consistently provide higher compressive strength than that of the corresponding wallettes specimens. A linear relationship between the compressive strengths of the prisms and the wallettes has been found appropriate. For the deformation characteristics of masonry, simplified analytical model is proposed to correlate the test data from the prisms and the wallettes.

Unsaturated behavior of excavations in residual soil at the Auburn University National Geotechnical Experimentation Site

Two excavations were instrumented at the Auburn National Geotechnical Experimentation Site (NGES) in Opelika, AL. The excavations were constructed approximately 6 m deep × 30 m long with a vertical face. The primary goal of this experiment was to determine the boundary conditions that resulted in failure of the excavation. In doing so, conclusions were drawn regarding the accuracy of common laboratory test methods for estimating the strength properties of residual soil. The instrumentation plan was designed to monitor real-time pore water pressures (positive and negative) surrounding the excavation throughout the course of each 1-year test period. Time-lapse cameras were used to identify when failures occurred, and the approximate geometry of the failure planes. Undisturbed soil samples were taken during the subsurface exploration and used in conjunction with previous soil test results to accurately define the material properties and layering based on common laboratory test methods. In addition to common laboratory tests, unsaturated triaxial tests were also conducted, and soil-water characteristic curves were measured to further define the unsaturated properties of the soil. In both excavations, failure was observed along a similar plane, which began at the bottom of the excavation, and propagated to the surface (approximately 2 m behind the face of the excavation) along existing tension cracks that developed during the construction of the excavation. Based on these results, recommendations are provided as related to the most appropriate test methods for determining the strength properties of residual soil for use in geotechnical design.

Thermo-mechanical forming procedure of high strength Aluminum sheet with improved mechanical properties and process efficiency

Abstract The rapidly rising demand of light-weight materials, especially high-strength Aluminum alloys, for structural components in the automotive and aerospace industries generates new challenges for the current metal producers and fabricators during the complex production and manufacturing process. However, a novel forming process for heat treatable Aluminum alloys - combining solution heat treatment and hot forming - promises a considerable improvement of formability with limited springback compared to the conventional forming techniques and, at the same time, the potential to improve mechanical properties and reduce processing times. In this study especially the effect of the solution heat treatment parameters on the improvement of mechanical properties of two different Aluminum sheet materials AA6082-T6 and AA7075-T6 is investigated. The impact and significance of the individual steps on the resulting properties and on the strengthening and formability behavior is characterized with the help of common material testing methods. A definite influence on the mechanical properties in the pre-aged as well as in the final aged condition is revealed with increasing heating rate, solution annealing temperature and duration as well as increasing cooling rate. On top of that a process time reducing interdependence of the parameters is observed, for instance increasing heating rates influence the dissolution kinetics and reduce significantly the necessary soaking time.

Mikronükleus Temelli Genotoksisite Testleri

Genotoxicity assessment is an important process to keep human and animal health and aims to identify the safety of many kinds of substances. There are many in vitro mutagenicity prediction tests. The recent in vitro/in vivo genotoxicity assays and accepted common test methods may give critical information for the assessment of genotoxic and probable carcinogenic potential of suspected substances. Micronucleus (MN), MN-FISH, MN-based flow cytometry analysis done alone or done with chromosome instability assays and/or comet assay are some of assays that may be used to assess clastogenic and aneugenic effects of substances like pesticides, food additives, pharmaceuticals, chemicals used in cosmetics, veterinary drugs and living organisms like bacteria or virus. In this mini-review, the studies about the tests mentioned above are included. In summary, MNbased genotoxicity tests and accepted common test methods may provide important information for the assessment of genotoxic and probable carcinogenic potential of suspected substances.

Soil water repellency after slurry fertilization in a dryland agricultural system

In the context of the circular economy, the use of animal excrements as fertilizers is encouraged, but the addition of such organic materials can develop soil water repellency (SWR) or hydrophobicity. There is a lack of consensus about how to assess SWR in agricultural soils. This work evaluated SWR when pig slurries were applied onto soil using the two most common testing methods: the water drop penetration time (WDPT) and the molarity of ethanol droplet (MED) tests. The experiment consisted of five different slurry treatments plus a control (no slurry added). At sowing, slurry from fattening pigs (SF) or no slurry application was combined with a second application at the cereal tillering stage, in which SF, slurry from sows (SS) or no-slurry were the treatments. Soil water repellency was tested at cereal tillering before slurry application and then during the following 47 days. At each sampling date, hydrophobicity was tested in undisturbed samples at field-moist and after 25 °C, 65 °C, and 105 °C oven drying. Disturbed samples were tested after 40 °C oven drying. Soil disturbance removed SWR. Under field conditions, undisturbed samples attained the maximum SWR expression 7d from pig slurry application; moderate and very severe scores using WDPT and MED were respectively attained. From 14d to the end of the experiment, the highest SWR was observed after 105 °C oven drying and when SF applications at sowing (900 kg TOC ha−1) had been combined with SS applications at cereal tillering (1894 kg TOC ha−1). Slurry hydrophobic compounds rather than slurry dry matter influenced SWR expression which is enhanced as the soil dries. The persistence of repellency (WDPT test) was more sensitive to detecting changes in SWR between treatments than the changes in its severity (MED test). The importance of the SWR described hereafter slurry application will depend on plant cover over the soil and the effects in slaking prevention in order to avoid superficial water runoff.

Magnetic focusing method and sensor in surface topography testing for ferromagnetic materials

As the precision of the manufacturing process and the quality of ferromagnetic parts are further enhanced, surface topography is playing a significant role in guaranteeing the service performance and lifetime of mechanical parts. Thus, a novel magnetic focusing method (MFM) that is not susceptible to a hostile environment in a sophisticated and online manufacturing process is proposed, which is demonstrated to be an effective and feasible technique with higher detection resolution and a higher signal-to-noise ratio (SNR). By a theoretical introduction of the magnetic focusing mechanism and finite element simulations and calculations for six main MFM sensor structural parameters, the MFM sensor characterizations and optimal structural parameters are presented. Furthermore, the feasibility and validity of the proposed novel method and sensor in surface topography inspection for ferromagnetic materials were verified in the experiments. Finally, the advantages and disadvantages of the common surface topography testing methods were compared. These results demonstrate the great promise in the application of MFM and the corresponding sensor in practical engineering.

Design-build-launch: a hybrid project-based laboratory course for aerospace engineering education

A project-based course involving the design, analysis, manufacturing, testing, and launching of mid-power solid-propellant rockets over a ten-week period has been developed and taught as an approach to enhance the education and preparation of aerospace engineers at the university level. The course consists of a sequence of structured laboratory assignments that expose students to common software tools, aerospace materials, manufacturing techniques, and testing methods that directly inform and run parallel to the project. Teams of four to five students complete the project (and portions of the labs) collaboratively within an engineering competition framework. Individual students within each team are assigned specific engineering roles (e.g. design engineer, manufacturing engineer) to create an interdependence that reflects a typical integrated product team in industry and exposes students to realistic social dynamics. Student teams conduct design reviews as progressive milestones for assessment, in addition to laboratory assignments. At a per-student cost on the same order as a textbook, the project-based course combines theoretical content from several subjects with a high-order learning approach (create, evaluate, analyze) to advance the engineering skills of university students.

ALK Testing Trends and Patterns Among Community Practices in the United States.

Targeted therapy of ALK in patients with metastatic nonsquamous non-small-cell lung cancer (NSCLC) and ALK rearrangements improves outcomes compared with chemotherapy. This study assessed real-world ALK testing patterns among community practices in the United States in patients with advanced (stage IIIB or IV) NSCLC. Patients age ≥ 18 years with two or more visits within the Flatiron Health electronic health record-derived database after January 2011 and diagnosed with stage IIIB or IV NSCLC through May 2017 were included in this analysis. Logistic regression was used to examine the association between demographic and clinical characteristics and testing for ALK rearrangements. Of 31,483 patients analyzed from the database, 16,726 patients (53.1%) were tested for ALK rearrangements. ALK testing rates were 66.9% and 18.5% in patients with nonsquamous and squamous histology, respectively. Average ALK testing rates increased over time from 32.4% in 2011 to 62.1% in 2016. Fluorescent in situ hybridization was the most common ALK testing method. Agreement between fluorescent in situ hybridization and other assays ranged from 94.1% to 97.9%. Median (interquartile range) time from laboratory receipt of sample to first ALK test result was 7 (7) days; median time from advanced diagnosis to first ALK test result was 25 (29) days. Patients who were older, male, had a history of smoking, lived in non-Western US regions, and who had recurrent disease or squamous histology were less likely to be tested for ALK. Patients with Medicaid and Medicare insurance were less likely to be tested than patients with commercial insurance. Overall, 21.5% of patients initiated therapy (20.4% chemotherapy) before receiving test results. ALK testing rates have increased over time. However, certain subgroups of patients are less likely to be tested, suggesting that additional education on molecular testing is warranted.

Dielectric response measurement of oil-paper insulation based on system identification and its time-frequency-domain conversion method

Dielectric response testing is a non-destructive insulation testing method that is widely used for assessing insulation properties. Time-and frequency-domain dielectric spectra are closely dependent on insulation conditions. In comparison with the time-domain spectrum, the frequency-domain dielectric response under sweep sinusoidal excitation has a stronger anti-interference capability and a more comprehensive insulation information. However, the wide application of the measurement using the frequency-domain dielectric response under sweep sinusoidal excitation is hindered by its long testing time. A possible solution is obtaining the frequency-domain spectrum by transforming the tested time-domain spectrum, such that the time- and frequency-domain spectra can be obtained in one measurement. Polarization depolarizing current measurement under DC excitation is a common time-domain testing method for time-frequency-domain conversion. However, such conversion is valid only at extremely low frequencies (less than 0.05 Hz), indicating a slight overlap with the frequency range of the measurement using the frequency-domain dielectric response under sweep sinusoidal excitation. Moreover, the effective conversion frequency range cannot be controlled manually, and the measurement using time-domain dielectric response under DC excitation is hindered by the anti-interference capability due to micro polarization-depolarization current. In addition, scholars have found nonlinearity in a partial insulation system. As the bridge of the traditional time-frequency-domain conversion, a linear extended Debye model cannot accurately reflect insulation materials that exhibit nonlinear characteristics, thereby further limiting the application scope of time-frequency-domain conversion. This study introduces the system identification theory to demonstrate the problems existing in the traditional time-frequency-domain conversion and proposes an improved time-domain testing method based on the previous work. The improved method extends the effective frequency range of time-frequency-domain conversion and emphasizes the comprehensive analysis of the insulation by combining the measured time-domain spectrum and the frequency-domain spectrum conversed from time-domain data.

Crystallographic texture and earing behavior analysis for different second cold reductions of double-reduction tinplate

Since the production of tinplate with non-earing properties is difficult, especially when it is produced via the double-reduction process, the optimal degree of second cold reduction is particularly important for achieving desirable drawing properties. The evolution of texture and the earing propensity of double-reduction tinplate with different extents of second reduction were investigated in this study. Optical microscopy and scanning electron microscopy were used to observe the changes in the microstructure at various extents of reduction. Two common testing methods, X-ray diffraction (XRD) and electron backscatter diffraction, were used to investigate the texture of the specimens, which revealed the effects of deformation percentage on the final texture development and the change in the grain boundary. The earing rate was determined via earing tests involving measurement of the height of any ear. The results obtained from both XRD analyses and earing tests revealed the same ideal value for the second cold reduction on the basis of the relationship between crystallographic texture and the degree of earing.

A New Approach for Investigation of Mode II Fracture Toughness in Orthotropic Materials

Abstract Estimation of mode II fracture toughness (KIIC) in composite materials is known as a troublous and crucial problem. Dissipated values of KIIC that are reported in different fracture mechanics references is the evidence of the mentioned claim. This problem can signify the necessity of modification on common test methods and fixtures. The present study focuses on the causes of shear test results scattering in composite materials and presents some solutions in the form of necessary corrections that should be performed on the common test fixtures. Mixed mode I/II fracture limit curves are employed to show that the scattering in test results have strong relation with the creation of a considerable Fracture Process Zone (FPZ). It is shown that common test fixtures are blind in confrontation with FPZ and are not able to active toughening mechanisms in pure mode II, correctly. Therefore, estimation of KIIC with available test fixtures has considerable standard deviation. After that, by employing some structural modifications on common fixtures, a new scheme of a shear fixture is proposed that in addition to include the FPZ effects, prepare suitable condition in order to activate the mode II toughening mechanisms. In this regard, it could be found that by applying these reforms, shear load concentration as well as the accuracy of empirical test and repeatability and reproducibility are enhanced. Furthermore, a 3D finite element method (FEM) was considered as the numerical method in which the Iosipesque and new fixture’s specimens were analyzed by ANSYS software. It was found that by applying major amendments in the new shear test fixture, a remarkable precision in results can be obtained in comparison with the previous Iosipesque one

Population Screening for Hemoglobinopathies.

Hemoglobinopathies are the most common single-gene disorders in the world. Their prevalence is predicted to increase in the future, and low-income hemoglobinopathy-endemic regions need to manage most of the world's affected persons. International organizations, governments, and other stakeholders have initiated national or regional prevention programs in both endemic and nonendemic countries by performing population screening for α- and β-thalassemia, HbE disease, and sickle cell disease in neonates, adolescents, reproductive-age adults (preconceptionally or in the early antenatal period), and family members of diagnosed cases. The main aim of screening is to reduce the number of affected births and, in the case of sickle cell disease, reduce childhood morbidity and mortality. Screening strategies vary depending on the population group, but a few common screening test methods are universally used. We discuss the salient features of population-screening programs around the globe as well as current and proposed screening test methodologies.

(104) - Order of heat and pressure tests impacts pain responsivity ratings

Considering the volume and variety of trials that use quantitative sensory testing (QST), accounting for potential order effects is imperative when determining the study protocol as well as for accurate data analysis. The present secondary data analyses examined whether the order of two common testing methods (heat and pressure) affected subsequent subjective participant pain ratings. 106 participants (50 females, mean age 30) underwent both thermal pain threshold and tolerance testing and pressure pain threshold testing in randomized order. Thermal pain threshold and tolerance was administered to the right ventral forearm using the Medoc Pathway with a .5 sec/minute rate of rise. Participants indicated when they first felt pain (threshold) and when it became intolerable (tolerance) by pressing a mouse button, which turned the device off. The temperature for each was recorded. Pressure was applied to the left and right trapezius muscle and the left and right thumb joint using an SBMedic algometer. Participants were instructed to say “pain” when they first felt pain as a result of the pressure stimulus. Heat and pressure were measured twice for each area, and an average was calculated for each testing method. T-tests revealed a significant order effect for pressure ratings, such that thermal testing performed first resulted in higher pressure ratings for both the trapezius (P = .013) and thumb (P = .025). Testing order was also significant for heat pain threshold (P = .049) and marginally significant for heat pain tolerance (P = .067), such that performing thermal testing first resulted in higher heat pain temperatures. These data suggest that order of testing impacts overall levels of pain responsivity, particularly in relation to heat and pressure, and could have implications for the interaction of other types of sensory testing (e.g. cold pain tolerance) as well. The current findings speak to the importance of controlling for testing order in QST data.

Trichomonas vaginalis and Chlamydia trachomatis co-infections

Trichomonas vaginalis and Chlamydia trachomatis co-infections

Mechanical Behavior Analysis of Y‐Type S‐SRC Column in a Large‐Space Vertical Hybrid Structure Using Local Fine Numerical Simulation Method

In a large spatial structure, normally the important members are of special type and are the safety key for the global structure. In order to study the mechanical behavior details of the local member, it is difficult for the common test method to realize the complex spatial loading state of the local member. Therefore, a local‐fine finite element model was proposed and a large‐space vertical hybrid structure was numerically simulated. The seismic responses of the global structure and the Y‐type S‐SRC column were analyzed under El Centro seismic motions with the peak acceleration of 35 gal and 220 gal. The numerical model was verified with the results of the seismic shaking table test of the structure model. The failure mechanism and stiffness damage evolution of the Y‐type S‐SRC column were analyzed. The calculated results agreed well with the test results. It indicates that the local‐fine FEM could reflect the mechanical details of the local members in a large spatial structure.

Low sidelobe level and high time resolution for metallic ultrasonic testing with linear-chirp-Golay coded excitation

Linear-chirp-Golay (LCG)-coded excitation combined with pulse compression is proposed in this paper to improve the time resolution and suppress sidelobe in ultrasonic testing. The LCG-coded excitation is binary complementary pair Golay signal with linear-chirp signal applied on every sub pulse. Compared with conventional excitation which is a common ultrasonic testing method using a brief narrow pulse as exciting signal, the performances of LCG-coded excitation, in terms of time resolution improvement and sidelobe suppression, are studied via numerical and experimental investigations. The numerical simulations are implemented using Matlab K-wave toolbox. It is seen from the simulation results that time resolution of LCG excitation is 35.5% higher and peak sidelobe level (PSL) is 57.6 dB lower than linear-chirp excitation with 2.4 MHz chirp bandwidth and 3 μs time duration. In the B-scan experiment, time resolution of LCG excitation is higher and PSL is lower than conventional brief pulse excitation and chirp excitation. In terms of time resolution, LCG-coded signal has better performance than chirp signal. Moreover, the impact of chirp bandwidth on LCG-coded signal is less than that on chirp signal. In addition, the sidelobe of LCG-coded signal is lower than that of chirp signal with pulse compression.

A novel method of calibrating a MEMS inertial reference unit on a turntable under limited working conditions

Micro-electro-mechanical systems (MEMS) inertial measurement devices tend to be widely used in inertial navigation systems and have quickly emerged on the market due to their characteristics of low cost, high reliability and small size. Calibration is the most effective way to remove the deterministic error of an inertial reference unit (IRU), which in this paper consists of three orthogonally mounted MEMS gyros. However, common testing methods in the lab cannot predict the corresponding errors precisely when the turntable’s working condition is restricted. In this paper, the turntable can only provide a relatively small rotation angle. Moreover, the errors must be compensated exactly because of the great effect caused by the high angular velocity of the craft. To deal with this question, a new method is proposed to evaluate the MEMS IRU’s performance. In the calibration procedure, a one-axis table that can rotate a limited angle in the form of a sine function is utilized to provide the MEMS IRU’s angular velocity. A new algorithm based on Fourier series is designed to calculate the misalignment and scale factor errors. The proposed method is tested in a set of experiments, and the calibration results are compared to a traditional calibration method performed under normal working conditions to verify their correctness. In addition, a verification test in the given rotation speed is implemented for further demonstration.

Effects of nano-layered silicates on mechanical and chemical properties of acrylic-melamine automotive clear coat

PurposeMechanical and chemical properties of acrylic-melamine automotive clear coat in the presence of different percentages of well dispersed nano-layered sodium montmorillonite (Na-MMT) silicate particles were investigated. For this purpose, prepared dry clear coat film samples were subjected to the entire standard test series, usually carried out in automotive coating industry.Design/methodology/approachEffects of adding different percentages of nano-layered silicate on mechanical and chemical properties of acrylic-melamine automotive clear coat were investigated. To increase the compatibility of nanoclays with polymer matrix of clear coat, the surface of nanoclays was modified by benzalkonium chloride as a cationic surfactant. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization and comparison between clays before and after modification, and also after dispersion in coating. Prepared dry clear coat film samples subjected to the test series are usually carried out in automotive coating industry.FindingsThe results indicated that incorporation of 1 and 2 Wt.% of nano-layered silicate caused desired improvement in chemical and physical properties of the acrylic-melamine clear coat. Increasing the percentage of nanoclay to over 2 Wt.% caused damage in some properties such as hardness, cupping and gloss.Research limitations/implicationsAll materials and methods were used in this research are industrial grade. Therefore, the introduced modified clear coat sample has potential for commercial production as an automotive clear coat.Originality/valueAs far as it was searched in the literature, effects of adding nanoclay particles on mechanical and physical properties of different clear coats, such as epoxy clear coat, have been investigated in a few researches, but in this research, common and special tests which are necessary in automotive coating industry have been ignored. In the present study for the first time, acrylic-melamine clear coat was subjected to modification using nano-clay, and also, the most common industrial test methods were used for investigation of mechanical and chemical properties.