Surface Testing Method Research Articles

Experimental study of penetration of pre-cut free surface rock materials based on orthogonal tests and response surface testing methods

The parameters of the pre-cut kerf as the free surface on rock material have an important influence on the rock-breaking force of the disc cutter of TBM. The rock-breaking force of the disc cutter can be simplified as the normal penetration load of the metal indenter. In order to study the effect of the pre-cut free surface parameters on the penetration load, orthogonal experiments and response surface tests were carried out on sandstone and granite samples, and extreme deviation analysis and analysis of variance (ANOVA) were performed. The results showed that: (1) the order of priority of the factors affecting the penetration load of the disc cutter was Kerf depth > Kerf spacing > Kerf angle. (2) The fitting degree of the regression equation for the predicted values of the penetration loads of the sandstone and granite samples was R2 (Sandstone) = 0.9810 and R2 (Granite) = 0.9995, respectively, indicating that there was a good fit between the measured and predicted values of the penetration load of the two samples.

Multi-indicator optimization of riveting joint forming quality of aluminum alloy sheets based on response surface test

In this paper, the effects of the interaction between punch diameter, die depth and punch speed on the quality of riveted joints are investigated using the BBD response surface test method. The results show that the mold depth has the greatest influence on the key dimensional parameters of riveted joints, followed by the punching speed, and then the punch diameter, while the punch diameter and the mold depth are the two factors with the most obvious interaction. The optimum riveted joint process parameters determined are punch diameter of 5.24 mm, die depth of 1.44 mm, and stamping speed of 5.00 mm/s. The corresponding relative errors predicted by numerical simulation and response surface optimization objective are 5.96 % for neck thickness, 3.29 % for interlocking value, and 1.37 % for bottom thickness; and the relative errors predicted by experimental results and optimization objective are 13.42 % for neck thickness, 13.42 % for interlocking value, and 1.37 % for bottom thickness. 13.42 %, interlock value is 4.23 %, and bottom thickness is 2.23 %, the model accuracy is high, and the optimization method of response surface test can effectively improve the quality of riveted joints. Through numerical simulation, the metal flow law and stress distribution during the riveting and forming process of aluminum alloy plate were analyzed, and the strength test of riveted joint was carried out, and the maximum destructive shear load of the joint was 1.8 KN, and the strength of the joint was improved, which verified the validity of the response surface optimization method.

Repeatability in fan sound ratings: Challenges faced in a certification program

The Air Movement and Control Association International (AMCA International) maintains a certified ratings program for published air and sound performance for fans. Sound test results can come from AMCA 300 reverberant room testing but are also accepted from manufacturers’ accredited labs using other international test standards covering in-duct, enveloping surface, and sound intensity test methods. Observed repeatability between these test methods and labs will be discussed. AMCA 301 covers sound calculation methods, including extrapolation to non-tested sizes and speeds. Requirements and practical recommendations for this conversion will be discussed. Surveillance for the program comes through periodic check tests on manufacturers’ products. The check test process provides an overall view of measurement and calculation variance, as well as inevitable manufacturing tolerances and their impact on sound. Finally, the results of round robin testing conducted on centrifugal, tube axial, and vane axial fans at various accredited sound labs will be reviewed.

The Misadjustment Error of a New Cylindrical Surface Testing Method

A cylindrical combination testing method is proposed in this paper. Three cylindrical mirrors are combined in pairs. By constructing a confocal optical system for interference testing to obtain combined wavefront aberration. The cylindrical surface errors are calculated by the combined wavefront aberration. The source of misalignment error is analyzed in detail and the mathematical model combined with the Chebyshev polynomial coefficients is established. That the misalignment error can be effectively removed by polynomial fitting is proved by simulation.

Research on Conductivity Damage Based on Response Surface Analysis

Hydraulic fracturing is an important means of developing unconventional oil and gas layers. The fracture conductivity of tight sandstone reservoirs after fracture is affected by many factors, such as the interaction between the fracturing fluid, water, and rocks; the fracturing materials; and the construction parameters. This paper improves the experimental process of the long-term conductivity test and provides insight into conductivity prediction and optimization based on the response surface test method. The test process is conducted in the following manner: (1) inject nitrogen to evaluate the fracture conductivity before fracturing fluid damage; (2) inject fracturing fluid to simulate shut-in; and (3) inject nitrogen again to evaluate fracture conductivity after the damage ability of the fracturing fluid. The single factor test results show that the lower the sand concentration is, the higher the fracturing fluid viscosity will be, and the longer the fracturing fluid retention time is, the greater the damage to the conductivity of the fracturing fluid will be. The response surface test results show that the order of factors affecting the retention of conductivity is fracturing fluid viscosity > sand concentration > fracturing fluid retention time. There is a certain interaction between sand concentration and fluid viscosity, and there is also a certain interaction between fluid viscosity and fluid retention time, but these interactions are not significant; when the fracturing fluid retention time is longer, there will be an interaction between the sand concentration and the fracturing fluid retention time. In addition, based on the model used to optimize the fracturing construction parameters from the perspective of proppant conductivity damage, the optimal solution is when the viscosity of the fracturing fluid is 1 mPa.s, the paved-sand content is 8.49 kg/m2, and the retention time of the fracturing fluid is 10 h. The maximum retention rate of the flow conductivity is 63.19%.

Toward accurate evaluation of bulk hardness from nanoindentation testing at low indent depths

Estimations of bulk hardness from nanoindentation are frequently subject to considerable uncertainties due to indentation size effects (ISE), pileup effects, and potential influence of surface quality or test methods. This study examined materials science principles of nanoindentation test methods to enable accurate prediction of bulk hardness for a series of high purity Fe and Fe-(3–25 wt%) Cr alloys. These materials were tested in as-annealed and thermally aged (100–900 h at 475 ℃ to produce Cr-rich α’ precipitates) conditions. Nanoindentation with a Berkovich indenter at constant strain rate (0.05–0.5 /s) and constant loading rate conditions provided comparable bulk equivalent hardness (H0) extracted by Nix-Gao model, indicating a weak strain rate sensitivity at room temperature. Results from electropolished and fine mechanically polished samples gave comparable measured hardness. Pileup corrections produced a 5–14% correction to H0 which agreed with the experimental bulk Vickers hardness within ∼10% for most tested materials. The microstructural model-predicted and measured strength values agreed for aged samples. A derived analytic expression demonstrates that an ISE error, associated with inappropriate methods such as hardness ratios or changes at a reference depth, would be as large as 60% in estimated bulk hardness for the investigated Fe-Cr alloys.

OPTIMIZATION DESIGN OF AN AIR-PRESSURE SUBSOILER TYPE

Through the mechanical analysis of air-pressure subsoiler, it is found that the main factors affecting its tractive resistance are the air pressure injected into the soil, the soil cohesion, the length and width of the shovel surface, the soil disturbance coefficient, and moving speed of the subsoiler. The traditional air-pressure subsoiler was redesigned to solve the problem of large tractive resistance. In the soil trench experiment, the subsoiling shovel’s shape, the air pressure, and the position of air hole were used as test factors, and the ratio of the traction resistance of the shovel to the soil disturbance, namely SDF (Specific Draft Force), was used as the evaluation index. By the response surface test method and analysing the soil disturbance and the tractive resistance, it is determined that rectangular subsoiling shovel with the air hole in the upper part of the shovel is the optimal under the pressure of 1.2 MPa.

Modification of Hydrophobicity of Concrete by Nanocomposite Particles

Water conservancy project is a project constructed to control and deploys surface water and groundwater in the natural world to achieve the purpose of harm removal and profit. Water conservancy projects need to build different types of hydraulic structures such as dams, dikes, spillways, sluices, water inlets, channels, and fish channels. These buildings all require concrete to be constructed, so the research on the hydrophobicity of concrete is very important. The purpose of this article is to solve the problem of high hydrophobicity of concrete in water conservancy projects. Based on the super-hydrophobic surface theory and test method, the nano-concrete mixing ratio is debugged and determined based on the ordinary concrete mixing ratio. Six types of modifications are formulated. And unmodified nano-SiO2 organic film-forming composite coatings, the effect of nano-composite particles on the hydrophobic properties of concrete was studied. Then the surface contact angle of the concrete after coating the nano-composite particles was measured, and the optimal amount of nano-SiO2 in the coating was determined. The research results show that adding an appropriate amount of nano-SiO2 to the coating can improve the roughness of the coating, so that the contact area between the droplet and the substrate is reduced, and the contact angle is increased. When nano-SiO2 is added in excess, SiO2 will produce agglomeration and contact angle. Instead, it will decrease; by measuring the water absorption of the coated concrete, it is found that the modified and unmodified nano-SiO2 can significantly improve the hydrophobic water of the coated concrete, among which the improvement of the modified nano-SiO2 is greater, and at the same time the water absorption of the concrete.

Challenges to Accurate Evaluation of Bulk Hardness from Nanoindentation Testing at Low Indent Depths

Estimations of bulk hardness from nanoindentation data are frequently subject to considerable uncertainties, due to indentation size effects, potential pileup effects, and potential influence of surface quality or test methods. In this study, we examined materials science principles of nanoindentation test methods to enable accurate prediction of bulk hardness for a series of high purity Fe and Fe alloys containing 3-25 wt. %Cr. These materials were tested in as-annealed and thermally aged (100-900 hours at 475 oC for 14-25 wt. %Cr) conditions to produce Cr-rich a’ precipitates of varying size and density (bulk Vickers hardness values of ~50 to 350 VHN). Nanoindentation performed with a Berkovich indenter using constant strain rate (0.05 to 0.5 /s) and constant loading rate test methods provided comparable bulk equivalent hardness (H0) extracted by Nix-Gao model, indicating a weak strain rate sensitivity of the investigated materials at room temperature. Results from electropolished and fine mechanically polished samples were found to give comparable measured hardness. Conversely, material pileup adjacent to the indented area produced a 7-20% correction to the indent contact area. The Nix-Gao fitted nanoindentation H0 after pileup corrections agreed quantitatively better with the bulk Vickers hardness than the uncorrected H0 values. The model-predicted (dispersed barrier hardening superposition) and measured strength values agreed for aged Fe18Cr, indicating that Nix-Gao model combined with pileup corrections significantly improved the accuracy of hardness evaluation by nanoindentation. Analytic and experimental analyses demonstrate that inappropriate methods such as hardness ratios or changes at a reference depth (applied in many prior nanoindentation studies) can cause quantitative errors in bulk hardness estimates as large as 60% due to indentation size effects.

Sensing performance of knitted strain sensor on two-dimensional and three-dimensional surfaces

Flexible strain sensors and their sensing performance have been attractive in human motion detection applications. In this project, a knitted strain sensor was designed and fabricated via the technology of weft-knitting a nylon/nylon-wrapped spandex/silver-coated yarn into a knitted garment. Locations of sensor areas were customized to form a whole piece of knitted garment popular for today's applications in elastic tight-fitting activewear. The sensor provides electrical resistance data as a wearable sensing device for detecting body motions. A new method of using a three-dimensional curved surface to evaluate the sensing performance of the knitted strain sensor was proposed. Compared with the method of two-dimensional test, the three-dimensional test method was closer to the actual human sensing situation when the knitted sensor is worn. The strain sensing range of the three-dimensional curved surface was 120%, twice the sensing range of the two-dimensional surface. This research indicated that this three-dimensional surface testing method could be effectively applied in the sensing performance evaluation of fabric strain sensors.

Efficiency of some commonly used disinfectants on bacterial isolates from critical areas of tertiary care hospital

Aim of the study: Monitoring bacterial susceptibility to antimicrobials and disinfectants may help the management of nosocomial infection. Environmental surfaces are epidemiologically important reservoir of nosocomial bacterial species. The successful eradication of these pathogens with antibiotics has been complicated by the development of highly resistant strains as well as the appearance of new virulent pathogens. Materials and Methods: Mop water with added disinfectant was collected from critical areas of the hospital which were- surgical operation theatre, ophthalmology operation theatre, and intensive care unit of medicine. Isolates were tested by surface test method for efficacy of 6 commonly used disinfectants; Sodium hypochlorite, Phenyl black, Povidone iodine, Lysol (cresol) - benzalkonium chloride, Chloroxylenol & Chlorhexidine for recommended dilutions. Results: Majority of isolates were from M-ICU. Strains representative of GNB (gram negative bacilli) were most prevalent as compared to NFGNR. Recommended dilution of all the disinfectant was found satisfactory except phenyl black. Recommended dilution for phenyl black is 1:200 in water and as per our results of the study; MIC and MBC of organisms were found to be high. So it is recommended to use it in the critical areas of hospital with caution. Conclusion: The problem of hospital infection is a real one. Antibiotic resistant NFGNR, especially Pseudomonas spp. have played a predominant role. Antimicrobial activity of disinfectants may be influenced by their formation, level of organic load, synergy, temperature, dilution rate and tests methods. Disinfectant testing strategies should be part of any healthcare infection control policy. Keywords: Disinfectants, Bacteria, Surface test.

Research on compensating stitching testing for convex aspherical surface

Aspherical optical elements bring much benefit to modern optical systems, due to its significant role in improving optical performance by compensating residual aberrations, and decreasing system’s weight. However, manufacturing aspherical surfaces in high accuracy is usually limited by the ability of surface metrology, especially for convex aspherical surfaces. In this paper, we propose a compensating stitching method combining computer generated hologram (CGH) compensating testing and stitching testing to achieve the full aperture map of convex aspherical surfaces. Firstly, we introduce our self-developed mathematical models in the compensating stitching method, including CGH design model, subapertures’ alignment model and stitching model. Then the performance of our proposed method is demonstrated with compensating stitching testing of an off-axis convex aspherical mirror with its aperture of 332mm×144mm. The experimental result shows that the convex aspherical surface can be tested in full aperture with our proposed method effectively, which demonstrates that our proposed surface testing method opens a new path for the testing of convex aspherical surfaces.

Ground Penetration Radar in Geotechnics. Advantages and Limitations

The use of the Ground Penetration Radar (GPR) in geotechnics presents great potential, but also relevant difficulties. This technique allows the acquisition of field data in a fast and versatile way, facilitating the interconnection between the geological studies, the geophysical characterization, the mechanical exploration and the geotechnical zoning. The depth and accuracy of data acquisition easily adapts to various situations ranging from a few centimetres to several tens of meters, changing to antennas with lower frequency. This near surface and non-destructive test method can be used almost anywhere. The continuity of the information obtained with the GPR complements the discreet and localized information obtained with the mechanical exploration. The validation of the local geological conditions using direct mechanical exploration together with the GPR imaging allows the confirmation of the parameters obtained by techniques of different nature, that once validated can allow the interpretation of areas and volumes with improved accuracy. In favourable conditions the use of the GPR can greatly help the direct mechanical exploration but the interpretation must always be done with great care and based on a good knowledge of the site characteristics. The interpretation of the GPR has in most cases many uncertainties. The research developed aimed at increasing the geotechnical characterization efficiency, using complementary techniques in order to reduce the costs and the time required to perform the geotechnical studies, ensuring that the information obtained is suitable and sufficient for the intended purposes. In a few case studies the GPR was used conjugated with trenches and the Dynamic Probing Super Heavy (DPSH) test, and allowed to enhance the individual information of each technique, increasing reliability, taking into account the importance of the geology of each site. In the geotechnical study for the rehabilitation of an ancient Villa, requiring the construction of a small auditorium in the basement and an underground garage in the garden, the GPR and the DPSH successfully allowed to define the geotechnical zoning of the surface soils and of the depth of the sandstone bedrock, as the local information obtained by the DPSH allowed to validate the GPR imaging. The presence of buried pipes and of an underground water tank were also identified by a GPR grid. In karst areas the interpretation of the GPR can be complex due to the irregular geological interface between the limestone and the residual soils filling the dissolution zones. In aeolian sands the layers structure and the change in grain size are usually well identified with the GPR imaging, which can be validated by the geological reconnaissance and the mechanical exploration. Besides the natural variation of the electromagnetic properties of the ground mass, unexpected causes like tree roots, uncontrolled fill or even previous excavations can difficult a clear interpretation of the GPR data.

一种针对超大口径凸非球面的面形检测方法

一种针对超大口径凸非球面的面形检测方法

Induction and conduction thermography: From the basics to automated testing taking into account low and high residual stresses

Abstract Active thermography via electromagnetic excitation is a non-destructive evaluation method with a wide range of applications. It is a quick and reliable means for detecting inhomogeneities like cracks at or close to the surface of conductive components utilizing infrared imaging. Electric current can be used in two ways for thermography: In induction thermography, a current is coupled to the component without contact by passing an alternating current through a coil which is in close proximity to the component inspected; in conduction thermography, the current is coupled directly with the component. In this paper, we present a review of the basics of this non-destructive evaluation method along with several component examples and examples of inspection systems. In particular, automated testing is regarded. Additionally, sufficient detectability of cracks under low and high residual stress is discussed and compared with other surface testing methods.

Modified surface testing method for large convex aspheric surfaces based on diffraction optics.

Large convex aspheric optical elements have been widely applied in advanced optical systems, which have presented a challenging metrology problem. Conventional testing methods cannot satisfy the demand gradually with the change of definition of "large." A modified method is proposed in this paper, which utilizes a relatively small computer-generated hologram and an illumination lens with certain feasibility to measure the large convex aspherics. Two example systems are designed to demonstrate the applicability, and also, the sensitivity of this configuration is analyzed, which proves the accuracy of the configuration can be better than 6nm with careful alignment and calibration of the illumination lens in advance. Design examples and analysis show that this configuration is applicable to measure the large convex aspheric surfaces.

Enhancement of electrical conductivity of composite structures by integration of carbon nanotubes via bulk resin and/or buckypaper films

Abstract This study describes two approaches for the incorporation of carbon nanotubes (CNTs) in carbon fibre reinforced polymer (CFRP) composites, through the addition of the CNTs in the bulk resin and by the addition of CNT-based buckypaper (BP) in the CFRP structure. Several laminates were successfully manufactured integrating these two approaches, where a significant improvement of the electrical conductivity (EC) values was found. Additionally, in order to compare different surface preparations and testing methods, a cross check of EC test was carried out among different laboratories. This characterization was complemented with scanning electron microscopy (SEM) analyses, results of which were used to rule out a complete filtering effect of the CNTs. Furthermore, interlaminar shear strength (ILSS) tests were also performed, with the aim of assessing the mechanical behavior of the different configurations.

Optimization of Key Technology for Instant Sea Cucumber Processing through Fuzzy Evaluation and Response Surface Methodology

The original flavor of instant sea cucumber products can be retained and these products consequently show good market potential. In this study, the key processing technique for instant sea cucumber was optimized on the basis of single factor through Box-Behnken response surface test method by using collagen and polysaccharide contents and fuzzy mathematics sensory score as response values. Results showed that cooking time, cooking temperature, sterilization time and sterilization temperature significantly affected the overall quality and sensory quality of instant sea cucumber products. The optimum processing conditions were as follows: Cooking time, 17 min; cooking temperature, 83°C; sterilization time, 10 min; and sterilization temperature, 103°C. Under these conditions, the collagen content, polysaccharide concentration and sensory evaluation were 5.263±0.020%, 1.021±0.068% and 97.27±0.85, respectively and these findings were consistent with the predicted values. This study revealed that the nutrient components of instant sea cucumber are efficiently preserved and thus provided technical guarantee for the processing and production of instant sea cucumber.

Convex Aspherical Surface Testing Using Catadioptric Partial Compensating System

Aspheric optical components are the indispensable part of modern optics systems. With the constant development of aspheric optical fabrication technique, the systems with large aperture convex aspheric optical components are widely used in astronomy and space optics. Thus, the measurement of the figure error of the whole convex aspherical surface with high precision comes to be a challenge in the area of optical surface manufacture, and surface testing method is also very important. This paper presents a new partial compensating system by the combination of a refractive lens and a reflective mirror for testing convex aspherical surface. The refractive lens is used to compensate the aberration of the tested convex asphere partially. The reflective mirror is a spherical mirror which is coaxial to the refractive lens and reflecting the lights reflected by the tested convex asphere back to the convex asphere itself. With the long focal length and large aperture system we can realize a lighter and more compact system than the refractive partial compensating system because the spheric reflective mirror is more easily to realize and can bending the light conveniently.

Study on Unproppant Waterfrac Flow Conductivity Mechanism and Test Method

The main reason for the success of unproppant water-fracs is that uneven crack surface can form a self-supporting which achieves the objectives of diversion. It needs two conditions, one is the surface roughness of the crack surface, the other is the shear-slip between fracture surfaces. In this paper, the influential factors and influence law of slippage and the mechanism of forming residual space when the crack closed are exposed with the finite element method. The preparation method of water-fracs self-supporting fracture surface combination and test method of flow conductivity are established. It supply the means by knowing water-fracs increasing production mechanism and suitable reservoir conditions.