Surface Profile Measurement Research Articles

Three-dimensional scanning of soil surface and furrow profiles using a portable and affordable unit

Soil surface and furrow profiles in soil dynamics research and applications are usually measured using manual profile meters and laser-based scanners. Manual profile meters are laborious to use, and laser-based scanners could be expensive and not portable. An approach was developed for measuring soil surface and furrow profiles using a portable and affordable 3D scanner. The developed approach was validated by using the 3D scanner to measure the width and depth of a V-groove (with known dimensions) created in three types of soils (coarse sand, Black Vertosol and Red Ferrosol) at different soil water contents moulded in a soil box. Average error of ±1.83% was found for all the three soil types and soil water contents. Results from the 3D scanner were also validated in the field by comparison to profiles measured with a pinned profile meter. In terms of percentage difference in readings, the 3D scanner results showed 16, 5 and 4% greater furrow width, ridge height and cross-sectional area, respectively, and 1% less furrow backfill. These differences were partly due to profile meter pins digging into loose soil and limitation with accurate width measurement. Data acquisition and processing with the 3D scanner unit were significantly faster than with the pinned profile meter. In general, it could be concluded that the developed methodology has the level of accuracy required for soil surface and furrow profile measurements. Furthermore, this approach is a cost-effective alternative to using laser-based scanners.

Field evaluation of rutting in concrete pavements

Surface wear by studded tires is a primary cause for rutting in portland cement concrete (PCC) pavements, and may, for the pavement sections with high traffic intensities, become a primary factor controlling the length of pavements maintenance intervals. In the present study, PCC pavement field performance with respect to surface wear is examined based on the transverse surface profile measurements performed yearly during first five years of pavements service life. Continuous transverse surface profile measurements have been performed yearly on a 20 km long rigid pavement section in Moscow region, Russia. Based on the measurements, quantitative parameters describing rut depth evolution are obtained and evaluated; the obtained results are discussed in context of previous research findings reported in the literature. The effect of pavement surface wear on the further rutting accumulation rate is examined. The particular attention is also given to the spatial variability of the measured pavement surface wear characteristics, i.e. rut depth and accumulation rate. The implications of the obtained results on the length of rigid pavement maintenance intervals are discussed.

Antimicrobial efficacy of cold plasma treatment against food-borne pathogens on various foods

The objective of this study was to assess the antimicrobial effects of atmospheric cold plasma decontamination treatment on foodborne pathogens on various foods. The study employed a 30 l chamber using surface dielectric barrier discharge as a plasma source applying an atmospheric pressure and ambient gases. The inactivation rates of three foodborne pathogens, E. coli O157:H7, S. Typhimurium, and L. monocytogenes, were examined in fresh vegetables, fruits, nuts, and powdered food samples in response to cold plasma treatment; several strains of each pathogen were evaluated. The hydrophobicity and surface roughness of selected samples were examined using the water contact angle and non-contact three-dimensional surface profiling measurements, respectively. Samples were then inoculated with the food pathogens and treated in cold atmospheric plasma for up to 20 min. As the treatment time increased, different levels of microbial reduction were observed among the samples and pathogens. Surface roughness was negatively correlated with the inactivation rate. Even surfaces showed higher microbial reduction. Taken together, these results indicate that surface roughness is an important factor for the antimicrobial efficacy of cold plasma treatment.

Exploiting forward-scattering asymmetry in imaging and surface profile measurements through scattering media

We propose a special imaging technique as a low-cost solution to profile hidden surfaces through scattering media. The method exploits the asymmetry property of a pair of identical laser beams in propagation through the scattering medium, where scanning the pointing of the paired laser beams allows for a collection of target samples to reconstruct the surface shape of a hidden object. In application, our new method provides alternative solutions to many real-world problems, such as medical imaging, optical communication, environmental sensing, and underwater surveillance that require dealing with a scattering environment that often obscures direct sight of a target area.

Cosine Error Elimination Method for One-Dimensional Convex and Concave Surface Profile Measurements

AbstractThis paper presents a novel method to eliminate cosine error in precision concave and convex surface measurement by integrating a displacement probe in a precision spindle. Cosine error in surface profile measurement comes from an angular misalignment between the measurement axis and the axis of motion and negatively affects the measurement accuracy, especially in optical surface measurements. A corrective multiplier can solve this problem for spherical surface measurement, but cosine error cannot be eliminated in the case of complex optical surface measurement because current tools do not measure such surfaces along the direction normal to the measurement plane. Because the displacement probe is placed on the spindle axis, the spindle error motion will affect the shape precision and surface roughness measurement of optical components such as mirrors and lenses, and the displacement probe will measure a combination of the spindle error motion and the geometry of optical surfaces. Here, the one-dimensional concave, convex, and hollow measurement targets were used, and cosine error was fundamentally eliminated by aligning the probe on the spindle always normal to the measured surface, and compensation was made for the aerostatic bearing spindle rotational error obtained by the reversal method. The results show that this proposed measurement method cannot only eliminate cosine error but also scan the large area quickly and conveniently. In addition, measurement uncertainty and further consideration for future work were discussed.

Quantification of additive manufacturing induced variations in the global and local performance characteristics of a complex multi-stage control valve trim

Control valves that are used in severe service applications have trim cages that are geometrically quite complex. Most of these trims are manufactured using traditional manufacturing methods which are expensive and time-consuming. In order to reduce manufacturing costs and shorten the product development cycles, Additive Manufacturing (AM) methods have been gaining popularity over the traditional manufacturing methods. Selective Laser Melting (SLM) is one of the most popular AM techniques. In this paper, the effect of the conventional Electron Discharge Machining (EDM) method and the SLM method on the performance characteristics of a complex multi-stage disc stack trim is investigated. Experimental tests conducted on the SLM trim showed that the flow capacity reduced in comparison to the EDM manufactured trim. Surface profile measurements indicated that the surface roughness of the SLM trim was significantly higher than the EDM trim. In order to evaluate the effect of surface roughness on performance in detail, well validated numerical simulations were conducted to compare the local performance of the valve trims manufactured by the two methods. The simulation results showed that the wall shear stress increases by 1.9 times on the trim manufactured by the SLM method due to the increased roughness.

High resolution depth and area measurements of low velocity impact damage in carbon fiber laminates via an ultrasonic technique

This research presents a method using high frequency ultrasonics to quantify the location, extent, and depth of damage in a carbon fiber laminated composite subjected to a low velocity impact (LVI) producing a Barely Visible Impact Damage (BVID) zone. Carbon fiber laminated composites are used extensively in a wide variety of industries from aerospace to athletic gear. Laminated composites provide a favorable strength to weight ratio but due to their layered structure an interior lamina can be damaged with little to no externally observed damage. This paper analyzes four in-house fabricated carbon fiber laminated composites with a custom high-resolution ultrasonic immersion C-scan system, that have been subjected to increasing levels of low velocity impacts (LVI's) to produce Barely Visible Impact Damage (BVID). Two mathematical techniques are used in analyzing C-scan data to obtain high image contrast and an unbiased ply-by-ply technique is used to create internal 3D profiles of laminate damage due to LVI's. These regions of damage are substantially larger than anticipated based off of surface profile measurements, thus significantly underestimating the reduction in the load carrying capacity of the damaged system. Finite element results of the reduction in load carrying capacity of simple plaques with a damage region obtained exclusively from surface observations of the damage zone indicate in each scenario investigated a reduction of 55–60% in load carrying capacity. Conversely, studies using the actual 3D damage zone from ultrasonic measurements indicate reduction in overall load carrying capacity for the same plaques a 65–75% reduction from that of the undamaged composite.

Dual differential confocal method for surface profile measurement with a large sensing measurement range.

To meet the requirements of the large sensing measurement range and high axial depth resolution for profile measurement, a dual differential confocal method (DDCM) is proposed in this paper. The DDCM uses the confocal signal to process separately the signal of two pinholes with axial offset, and it adds the two processed signals to obtain an axial response curve with a large slope and linear response range, thereby achieving a high-precision surface profile measurement with no axial scanning. Preliminary experiments show that the DDCM has a sensing measurement range of 0.54 µm and an axial resolution of 1 nm at the numerical aperture of 0.9. Furthermore, the sensing measurement range of the DDCM is approximately 2.9 times that of the differential confocal microscopy.

Accelerated Pavement Testing of Perpetual Pavement Test Sections under Heavy Aircraft Loading at FAA’s National Airport Pavement Test Facility

Abstract Six flexible pavements were constructed for construction cycle 7 (CC7) at the Federal Aviation Administration (FAA) National Airport Pavement Test Facility in Atlantic City, New Jersey. Four test sections on the north side measure 200 mm (LFP-4), 250 mm (LFP-3), 300 mm (LFP-2), and 375 mm (LFP-1) that are made of hot mix asphalt (HMA) over an aggregate subbase (thickness varying between 850 and 1,025 mm) resting on a subgrade with a California bearing ratio of 5.5. The fifth test section, LFC-5, is conventional flexible pavement with 125 mm of HMA over aggregate base and subbase, and the LFC-6 structure is the same as LFC-5 except that the crushed stone base layer is replaced with asphalt-stabilized drainable base. The objective of CC7 tests is to develop perpetual pavement design criterion and to validate or refine the fatigue model for HMA in airport pavement thickness design software FAARFIELD. The HMA fatigue model is based on the ratio of dissipated energy change (RDEC). Four fiber optic strain plates were installed to measure transverse and vertical strains at top and transverse strains at bottom within the HMA layer. Full-scale accelerated pavement tests were performed. Traffic test load parameters were six-wheel gear, 245-kN wheel load (gear load 1,470 kN), and 4-kmph speed. Pavement performance was monitored using crack maps, straight edge rut depth, and surface profile measurements. LFC-5 and LFP-4 showed significant fatigue cracks and rutting. LFP-1 and LFP-2 performed well with no signs of cracking. This article presents a discussion on the RDEC fatigue model, pavement thickness design, pavement material characterization test results, pavement instrumentation, accelerated pavement tests under heavy aircraft gear loads, and pavement responses measured using embedded sensors. The test section performance shows that, under loading conditions used in the study, by increasing HMA thickness from 25.4 to 30.5 cm, fatigue cracking was eliminated for the duration of testing (38,000 passes).

CNC machining of large FRPC parts employing workpiece localization and toolpath adaptation

In large fiber-reinforced polymer composite (FRPC) parts manufacturing curing process causes residual stresses in the material, which tend to deform the part after demolding. The geometry variability and the positioning variability on the machine table need to be measured and the toolpath adopted before machining. This requires part positioning within narrow tolerances. The availability of optical measuring devices has facilitated the exact part geometry and location measurement directly on the machine table. This study aims to implement the measurement on the machine table, localization in the machine coordinate system and toolpath generation based on the measured surface profile. The proof of concept was performed in a case of a large FRPC part manufacturing for wind industry.

Measurement of Inner Surface Profile by Laser: Mapping of Three-Dimensional Structure of Ear Canal

Measurement of Inner Surface Profile by Laser: Mapping of Three-Dimensional Structure of Ear Canal

Application of profilograph for evaluation of mechanical tillage of slope lands

In this paper, we analyze a wide range of measurements of the day surface profile of tilled soil in order to substantiate the moving average method for evaluating morphological parameters and studying the influence of the base profile length on the accuracy of the obtained values. The surface roughness of the elementary plot was 4 mm, the surface ridgeness formed by technological furrows was 16 mm, and the slope of the plot was 0.198. The accuracy of the obtained values of roughness and ridgeness of the tilled soil surface depends significantly on the profile length determined by the number of measurements performed. We obtained 5273 data points per one turn of the device on a 6.3 m profile length (1 measurements are made per 1 mm) for the elementary plot. The surface roughness varied from 3, 1 mm to 4, 3 mm, and the ridgeness – 12 ... 21 mm when the number of measurements is from 2000 to 5273. When the measured profile length is about 1.3 m or less (not more 2000 points), the parameters of the tilled soil cover are not considered important. However, they are more critical for ploughed soil than for harrowed soil. On flatter surfaces, the base profile length of 2.5 m may be sufficient to adequately calculate the parameters of the day soil surface.

一种微米级高度台阶镜面条纹反射的三维测量系统

一种微米级高度台阶镜面条纹反射的三维测量系统

Improving the extracting precision of stripe center for structured light measurement

The accuracy of the stripe center extraction is affected by the uneven reflectance and large curvature change of the object surface in the structured light three-dimensional measurement system. Aiming to eliminate the stripe distortion and improve the accuracy of stripe center extraction, an improved stripe center extraction method is proposed for structured light measurement. By analyzing the principle of stripe distortion and the types of stripe noises, the mean filtering is used to eliminate the noises. Then, a stripe preprocessing method is presented to adjust the gray scale of stripe distortion. Finally, stripe centers are extracted through the curve fitting method by preprocessing. Furthermore, the proposed method addressed the problem of local discontinuity of the stripe center caused by the unevenness of brightness in the measurement of complex surface profiles. The proposed method has been validated and verified by experiments. A high accuracy in the extraction of strip centers could be obtained.

Modeling of a Microscale Surface Using NURBS Technique

This article describes microscale surface modeling using the Non-Uniform Rational B-Spline (NURBS) surface interpolation technique. A three-dimensional surface model was generated on the basis of measured surface profile data. To validate this model, three brass specimens having different roughness values were used. Direct comparison between measured profiles and the curves modeled with NURBS was employed. It was identified that the proposed method allows the generation of microscale models similar to actual surfaces. Finally, a method to extract the Bearing Area Curve (BAC) from a 3D model was detailed. The proposed modeling will be useful for the characterization of bearing capacity of the surface and for contact analysis.

The Effect of Acetone Dilution towards the Surface Topography and Morphology of Micro Bearing Concept for Epoxy Filled UHMWPE Composite

Surface topography and morphological behaviours are the important aspects in the application of surface bearing as it deals with the contact area of objects upon motion. Improved surface bearing will be set as an indicator for tribology behaviour to reduce the possibility of wear rate and reduce the friction of objects, respectively. Thus, in this study, the fundamental of micro bearing concept was imparted as the Ultra High Molecular Weight Polyethylene (UHMWPE), which is a low density filler, will float onto the surface of the composite system to become a solid lubricant upon curing. UHMWPE filler, which is commonly known for its dominant properties of high tendency to resist wear and has low coefficient of friction were fabricated alongside epoxy resin in the composite system to achieve the desired strength and durability to perform over time. However, there are limitations of UHMWPE during processing upon the dispersion of the fillers with the matrix particles due to epoxy resin that has relatively high in viscosity. Therefore, acetone has been selected as a diluent with ratio of 1:1/4, 1:1/3, 1:1/2, 1:1 to dilute the high viscosity epoxy resin. The surface profile measurement were examined using Alicona Infinite Focus and Polarized Optical Microscope. Based on the results observed, EpUPE3 (epoxy and UHMWPE with acetone ratio of 1:1/2) showed better surface distribution and morphology with relatively low value of surface roughness (Ra) which is 1.41 µm and low pseuodocolour value of surface height which is around 6.76-6.77 cm compared to other formulation ratio. In near future, these surface topography and morphological analysis are important to relate with tribological, physical and mechanical properties of the micro bearing layers for bearing applications, specifically.

Synthetic wavelength to increase the snapshot optical sensor's elevated vertical measurement ranges.

Screening manufactured products that are conducted faster to enhance the contemporary manufacture processes and quality is possible by implementing enhanced quality control. Such quality control of manufactured products has increased the market for process-focused precision metrology that can execute evaluations faster while providing significant feedback for the manufacturing system. This investigation examines spatial dispersive interferometry's potential for producing accurate surface profile measurements by emphasizing vertical range measurements and identifying a system that can enable them to increase incrementally while maintaining the results' quality. Thus, this investigation selected Fourier transform profilometry (FTP) to assess surface profile measurements, as it provides the most reliable and fastest outcome data regarding this sensor. Exploring new surface scanning methods is important, as crucial weaknesses hinder several common approaches. As optical metrology sensors are bulky, difficult to establish, and expensive, the investigation will prove that FTP can resolve these restrictions. The investigation uses the synthetic wavelength approach for addressing vertical measurement limitation concerning optical systems for extending surface step height's vertical measurement range. Though it was observed that the FTP technique surmounts the vertical height limitations, certain limitations were also noted, with all outcomes considering key variables, including the scanning objective lens, system resolution, the spectrometer resolution, and diffraction grating. Future examinations must examine a wider vertical range to expand the snapshot spatial dispersive interferometry process's scope. Further, the step-height repeatability is enhanced, showing a good outcome range from 22 to 20 nm.

Residual stress compensated silicon nitride microcantilever array with integrated poly-Si piezoresistor for gas sensing applications

This work reports a novel method of microfabrication for silicon nitride based piezoresistive microcantilever device, to minimize the residual stress induced bending. The microcantilever of dimension L × W ~ 250 × 100 µm2 with stack (Si3N4/Poly-Si/Si3N4/SiO2) thickness ~ 1 µm was realized, by using standard six masks and bulk silicon micromachining fabrication process. In order to compensate the residual inbuilt stress, asymmetric structure layers for microcantilever was proposed and the presence of thin oxide layer underneath the released microcantilever stack was used to control the bending. The surface profiler measurement results showed the curvature bending in the range of ~ 4 ± 3 µm. The microcantilever was characterized further to evaluate its physical parameters such as mechanical deflection sensitivity and spring constant. The deflection sensitivity and spring constant values were ~ 0.161 ppm/nm and ~ 0.2 N/m, respectively. Finally, the practical application of fabricated piezoresistive microcantilevers was demonstrated by using it for explosive vapors sensing.

Three-dimensional surface profile measurement of a cylindrical surface using a multi-beam angle sensor

To investigate the application of the multi-beam angle sensor (MBAS) to high-precision optical aspheric and freeform surfaces, which are critical components in optical systems, we present a method of using an MBAS to reconstruct an aspheric surface from angle data. The MBAS is based on a multi-autocollimator system with a microlens array, which can split the beam into several spots and can convert centroid detection of the light intensity into an angle measurement. The MBAS is designed to address the curvature-range problem via a circumferential scan better than other methods and automatically eliminates the tilt error caused by rotation of a workpiece. Using a tracking technique, the MBAS can automatically determine focal spot positions from the centroid measurement of the light intensity. This is directly related to the accuracy of the angular difference measurement. The experimental results confirm the feasibility of using an MBAS for 3D surface profile measurements of cylindrical surfaces.

The Improvement of Turbulent Heat Flux Parameterization for Use in the Tropical Regions Using Low Wind Speed Excess Resistance Parameter

AbstractReliable simulation of turbulent heat fluxes needed for modeling land‐atmosphere interactions remains a challenge over the humid tropical region. This may be connected with the inadequate parameterization of the roughness lengths for momentum (z0m) and heat (z0h) transfer usually expressed in terms of excess resistance factor (κB−1). This paper assesses the performance of existing κB−1 schemes developed for high wind speed conditions over the humid tropical region. Thereafter, a more appropriate κB−1 suitable for low wind speed condition is developed for use in the aerodynamic resistance parameterization. Based on observed surface heat fluxes and profile measurements of wind speed and temperature from Nigeria Micrometeorological Experimental site, new κB−1 parameterization was derived through the application of the Monin‐Obukhov similarity theory and Brutsaert theoretical model for heat transfer. The derived , where Re* is the Reynolds number. Turbulent flux parameterization with this new formula provides better estimates of heat fluxes with reference to results from existing κB−1 schemes. The R2 increased by about 85%, while mean bias error and root‐mean‐square error in the parameterized QH based on the derived κB−1 reduced by about 63% and 66.7%, respectively. Similarly, the R2 increased by about 38%, while mean bias error and root‐mean‐square error in the parameterized QE based on the derived κB−1 reduced by about 47.8% and 52.6%, respectively. The derived κB−1 gave better estimates of QH than QE during the daytime. The derived κB−1 scheme corrects a well‐documented, large overestimation of turbulent heat fluxes, and it is therefore recommended for use in regions where low wind speed is prevalent.