Laser Profilometer Research Articles

New Approach to Determining the Roughness of Bicycle Roads

The international roughness index (IRI) is one of the important criterion used to determine the roughness of roads. Various devices are available to determine IRI, however, they are mostly used to determine the condition of highways. Studies to determine the roughness of nonmotorized roads, such as bicycle roads, which have become increasingly important in recent years, are limited. Therefore, this study presents a cost-effective roughness measurement method that can measure both highways and nonmotorized roads. For this, a mountain bike was used as the test vehicle, and for the first time, the stiffness and damping coefficients of the bicycle tire were taken into account when calculating the IRI. First, the stiffness and damping coefficients of the bicycle’s front tire were calculated. These coefficients were then used as input data for the equation of motion with one degree of freedom, and the IRI was calculated. The 660-m long divided highway (1,320 m in total) on the Bursa Uludagğ University campus was chosen as the test road. A laser profilometer device was used to quantify the reference IRI values of this test road. The same road was then measured by bicycle. The obtained results were evaluated using mean absolute percent error, mean absolute error, root mean square error, and mean square error metrics. All these indicators showed very promising results, suggesting that this new method could be a cost-effective and reliable approach to determining the IRI of highways, especially nonmotorized roads.

A novel hydraulic bulge test in hot forming conditions

A novel hydraulic bulge test device was developed to evaluate high temperature biaxial stress–strain curves of quenchable boron steel sheets. The work mainly focuses on the resistance heating designed to assure a homogeneous temperature field in the dome area of the circular blank where the hydraulic pressure will be applied. The practical hot stamping conditions, including the heating and cooling steps, were reproduced to perform hydraulic bulge tests on the Usibor ®1500P steel for a temperature range between 700 to 900 °C, after an austenization step at 900 °C. Stress–strain curves were obtained from these expansion tests using the data extracted with a laser profilometer, due to the difficulties associated with the use of Digital Image Correlation at such high temperatures. Although the profilometer is a compromise solution, the comparisons between tensile and biaxial stress–strain results enable to verify the feasibility of the new device for the evaluation of the stress–strain curves at a high temperature in a biaxial state. The results point-out that, besides the difficulties with the acquisition of the strain fields and in the strain-rate control, there are also challenges in the interpretation of the metallurgical evolutions that can occur during the tests, which can affect the biaxial flow curves.

Acoustic Roughness Measurement of Railway Tracks: Running Surface Detection and Compensation of Lateral Movements for Optical Measurements on a Train.

Rolling noise is a significant contributor to railway noise. Wheel and rail roughness are decisive for the emitted noise level. An optical measurement method installed on a moving train is suitable for closer monitoring of the rail surface condition. A measurement setup based on the chord method requires the sensors to be positioned in a straight line along the direction of measurement and in a stable lateral position. Measurements should always be performed within the shiny and uncorroded running surface, even when there are lateral movements of the train. In this study, concepts for the detection of the running surface and the compensation of lateral movements are investigated in a laboratory setting. The setup consists of a vertical lathe with a ring-shaped workpiece that incorporates an implemented artificial running surface. The detection of the running surface based on laser triangulation sensors and a laser profilometer is investigated. It is shown that the running surface can be detected using a laser profilometer that measures the intensity of the reflected laser light. It is possible to detect the lateral position and the width of the running surface. A linear positioning system is proposed to adjust the lateral position of the sensors based on the running surface detection of the laser profilometer. When the lateral position of the measuring sensor is disturbed by a movement with a wavelength of 18.85 m, the linear positioning system can keep the laser triangulation sensor inside the running surface for 98.44% of the measured data points at a velocity of approximately 7.5 km h-1. The mean positioning error is 1.40 mm. By implementing the proposed system on the train, future studies can be conducted to examine the lateral position of the running surface as a function of the various operational parameters of the train.

In Situ Analysis of Curling Defects in Powder Bed Fusion of Polyamide by Simultaneous Application of Laser Profilometry and Thermal Imaging

Additive manufacturing (AM) is one of the key technologies in the global manufacturing market within various application sectors. The unique capabilities of AM enable high structural and part complexity, low material waste, and benefits in productivity by reducing design cycles and time to market. Efficient real-time quality control is still an important challenge in AM. In this paper, a real-time and in situ approach for monitoring the process in powder bed fusion of polyamide (PBF-LB/P/PA12) is proposed using the simultaneous application of two individual sensors, enabling the overlay and direct comparison of independent output data. An industrial grade laser profilometer and a thermal infrared (IR) camera were successfully integrated into a commercial system for PBF-LB/P. Artificially created curling defects were induced in a reproducible way by the manipulation of process parameters. The radiometric data was evaluated and processed into 3D topology and profile measurements to highlight peaks and curling progression. The results measured using different powder bed conditions were contrasted with corresponding thermographic data to prove the thermal visibility of curling and the influence of inhomogeneous temperature distribution on geometrical powder surface defects. The experimental setup enables the measuring of the entire powder bed surface inside the machine, with no limitations to sub-areas. Results indicate the measurable presence of curling and related temperature influences. When curling reached maximum values, inverted warpage into the negative z-direction was detected at part center as a further effect. These results can be used for improving real-time quality control in AM.

Fractal analysis of anisotropic shear-fracture roughness from rocks and analogue laboratory models: A new approach for heterogeneous-slip characterization

Shear fracture surfaces are commonly rough on varied scales, and understanding the roughness properties is crucial to predict their slip behaviour. Using natural rock samples from the Singhbhum Shear Zone, eastern India, this study develops an approach to heterogeneous surface roughness analysis of shear fractures, forming two distinct domains: striated, anisotropic zone and non-striated, isotropic zone. Analogue experiments run on brittle-ductile models under a pure shear condition produce similar heterogeneous roughness characteristics of shear fractures. Using a laser profilometer, we constructed 3D topologies of both natural and experimental shear surfaces, which are presented to show the distinctive roughness characteristics of the striated and non-striated zones in terms of their fractal properties. ΔD, which stands for the difference between across- (D⊥) and along- (D∥) the slip direction, is calculated to evaluate the degree of their roughness anisotropy. This fractal parameter indicates strong anisotropy with ΔD = 0.0787–0.2118 in striated zones, which is significantly weak, where ΔD = 0.0024–0.0603 in non-striated zones. Finally, the article presents an in-depth discussion of this roughness study from the perspective of slip-stuck kinematics on shear surfaces from laboratory experiments and their geophysical implications, e.g., interpretation of earthquake event patterns on seismic faults and permeability of fractured rocks.

Roughness Control of Surfaces Using a Laser Profilometer with the Selected Material Cutting Technology.

The article aims to assess the roughness of parting surfaces in the context of abrasive water jet technology for various materials. The evaluation is based on the feed speed of the cutting head, which is adjusted to achieve the desired final roughness, taking into consideration the stiffness of the material being cut. We used non-contact and contact methods to measure selected parameters of the roughness of the dividing surfaces. The study included two materials-namely, structural steel material S235JRG1 and aluminum alloy AW 5754. In addition to the above, the study involved using a cutting head with varying feed rates to achieve different surface roughness levels required by customers. The roughness parameters Ra and Rz of the cut surfaces were measured using a laser profilometer (laser profilometer). To ensure the accuracy of the laser profilometer, a control roughness measurement was conducted using a contact roughness gauge. The roughness values obtained for Ra and Rz from both measurement methods were plotted on a graph to illustrate their dependencies and were subsequently evaluated and compared. By measuring the roughness parameters Ra and Rz, the study was able to provide insights into the effectiveness of the cutting head's feed rates in achieving the desired roughness levels. Additionally, by comparing the results of the laser profilometer and contact roughness gauge, the accuracy of the measurement non-contact method used in the study was verified.

THE ASSESSMENT OF NATIONAL ROAD SURFACE CONDITIONS ANALYSIS BASED ON THE INTERNATIONAL ROUGHNESS INDEX (IRI) METHOD USING ROADBUMP APPLICATION

Roads are infrastructure that has a vital role for the community in supporting social and economic activities. Therefore, appropriate handling information is needed for road maintenance and improvement to be on target. One of the methods used is the International Roughness Index (IRI) method with the help of the Road bump application. The purpose of this study is to analyze and recommend handling road surface conditions, as well as to test the validity of the Road bump application with a Laser Profilometer. This research was conducted on the 10 KM section of Trans Kalimantan Road. Comparative data is obtained from secondary data issued by BPJN in 2021 using the Laser Profilometer tool. This study found that the condition of the Trans Kalimantan Road was 80% in the excellent category, 18% in the moderate category, and 2% in the slightly damaged category, and had similarities with the BPJN IRI value of 95%. Road bump also tends to the IRI value to be greater than the BPJN IRI value. Based on the results of this study, the Road bump application can be used as an alternative tool for measuring road surface conditions using the International Roughness Index (IRI) method.

(High-Temperature Energy, Materials, & Processes Division Subhash Singhal Award) From Electrochemical to Mechanical Modeling of SOFCs and Their Experimental Validation

Tohoku University has been conducting research on the mechanical reliability of SOFCs under the financial support by NEDO (New Energy and Industrial technology Development Organization, Japan). Both numerical and experimental approaches have been taken at various levels, from electrochemical to structural analyses. An in-house code, SIMUDEL, was developed to simulate oxygen potential distribution inside the constituent materials in order to account for the chemical strain in cell/stack analyses. Non-linear stress-strain behaviors and inelastic deformation of the materials were characterized to improve the accuracy of the simulation. Predicting actual cell behavior, however, is still difficult, as unexpected factors often remain for each specific case. It is thus important to have in-situ or operando tools to observe the behavior of cells, such as deformation and stress generation. For that purpose, laser profilometer and X-ray stress analyzer were employed with a specially designed cell holder. Methods for evaluating local current density was also proposed. Currently, we are developing a protocol for testing robustness of planar SOFCs. Severe condition tests will be performed, and the results will be analyzed with the above-mentioned simulation.

Impact of MHT9002HV Tracked Harvester on Forest Soil after Logging in Steeply Sloping Terrain

The article presents the results of measurements regarding the impact of the MHT9002HV tracked harvester on surface deformations and changing the physical parameters of the soil of three operational trails. The measurements were made in the terrain with a longitudinal slope of up to 14.9° (33.2%) and a transverse slope of up to 8.8° (17.9%). Spruce deadwood trees in mountain forest habitats were harvested. Static Eijkelkamp Penetrologger 0615SA and dynamic own design penetrometer were used to measure penetration resistance, soil samples were taken to determine bulk density, moisture content, and ground deformations on the trails were measured with a laser profilometer. A statistically significant increase in soil penetration resistance measured with penetrometers occurred for trails in the left rut at a depth of 16–20 cm. The change in the bulk density and moisture content proved statistically insignificant. The maximum ground deformation on the trails reached an average of 5.9 cm. The selection of a machine with low unit pressures (33 kPa), under the given favorable atmospheric conditions (there was a high temperature reaching 35 °C), with low soil moisture, protective organic layer of high thickness, and post-limbing residues, was optimal. The comparison of the results of the compactness measurements made with different penetrometers shows that the values obtained for the static penetrometer 0615SA are lower than those of the dynamic penetrometer of our own design. This is due to the lack of registration of high compactness in the memory of the 0615SA device. In the case of the impact penetrometer measurement, this problem does not occur, however, the presented solution does not allow performing a large number of measurements, and data processing in the case of such a simple solution is tedious. There is a need to develop a new penetrometer useful for determining soil compaction under similar difficult measurement conditions.

A novel hand-eye semi-automatic calibration process for laser profilometers using machine learning

Hand-eye calibration is a vital step in the laser profilometer integrated measurement system. However, the widely applied standard sphere calibration process requires extensive laborious human work and expertise. To standardize and streamline the hand-eye calibration process for Industry 4.0, a semi-automatic calibration process was proposed, containing a calibration postures generation model and an intelligent circle detection method based on machine learning. With the proposed process, the measurement system can collect required data with minimal human participation and automatically processes them, which can significantly improve hand-eye calibration accuracy and efficiency. Additionally, an exhaustive study of the influence of the number of postures on the calibration accuracy of the industrial robot and automated fibre placement (AFP) machine demonstrates the proposed model’s effectiveness. Moreover, the current study’s results can also be excellent tools for further hand-eye calibration research. Our code and dataset are made publicly at: https://github.com/tangyipeng100/hand_eye_cali_circle_segmentation.

Theoretical and Experimental Study on Normal Contact Stiffness of Plane Joint Surfaces With Surface Texturing

Effects of surface texturing on normal contact stiffness have been investigated by experiments in previous research studies; however, there are relatively few theoretical models in this regard. This article aims to investigate the influence of surface texturing on the normal contact stiffness in theory and experiment. In the present research, a rough surface with surface texturing is divided into two parts, the textured zone and the remaining zone, and their theoretical models of normal contact stiffness are established respectively, considering surface morphology and material properties. For the textured zone, microtextures are modeled theoretically based on the three-dimensional topographic data obtained via a laser profilometer. For the remaining zone, the surface topography is characterized based on fractal theory, and a calculation model is established considering the elastoplastic deformation of surface asperities. In the experiment, the normal contact stiffness of specimens is obtained through the self-developed experimental platform. The proposed theoretical model is appropriate through the comparison of test results and theoretical predictions. The research results show that the effect of surface texture on the contact stiffness is related to the surface roughness, Sa. For the joint surfaces with Sa > 2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.

New methods and functionalities for railway maintenance through a draisine prototype based on RADAR sensors

AbstractInspection of the railway tracks requires relying on a precise positioning system that accurately determines the location of potential failures and deficiencies. Therefore, measuring the speed and precise location of rail vehicles is essential. Many methods and approaches have been proposed, but most of them lack several conditions that do not allow them to be optimal for this task. In this paper, the authors present a novel method for measuring the speed of a train by means of the time correlation approach, by using 2‐mm wave radar sensors. Additionally, it is also an accurate positioning system because the authors prove that the track has a unique profile, sufficiently characteristic and stable over time, that serves as a distinctive signature, which can be used to locate the vehicle at any point on that track. As a result, this new methodology, combined with a laser profilometer device, can be used as an effective inspection system for cracks or deficiencies in the rails, sleepers, fastenings, bolts etc., locating them precisely on the railway track.

Experimental Detection of Nonlinear Dynamics Using a Laser Profilometer

This paper investigates a cantilever beam nonlinear dynamic behaviour, on which the nonlinearity is introduced with permanent magnet interactions or with a non-holonomic contact. The experimental time domain responses obtained from non-zero initial conditions are measured using a laser profilometer, conventionally adopted for product shape detections in online industrial applications. The Fourier transform, Continuous Wavelet transform, and Hilbert transform are used to investigate nonlinear phenomena in the frequency content, highlighting advantages and drawbacks of the three methods in catching instantaneous phenomena. Then, a Multi-Phi approach is proposed to describe the time evolution of nonlinear systems by means of a discrete number of linearised systems. Therefore, two linearised models have been developed and tuned to describe the dynamic behaviour of different Euler–Bernoulli cantilever beam configurations. The experimental data of nonlinear systems are compared with the corresponding ones of the linear system to evaluate the effects of introduced nonlinearities on the overall dynamic properties.

THE ASSESSMENT OF NATIONAL ROAD SURFACE CONDITIONS ANALYSIS BASED ON THE INTERNATIONAL ROUGHNESS INDEX (IRI) METHOD USING ROADROID APPLICATION

Road infrastructure is built as an infrastructure to meet needs and facilitate accessibility and mobility of socio-economic activities in the community. With the benefits that are so important, therefore the road construction and maintenance sector become a priority to be researched and developed in planning, implementing, and maintaining it. At the location of Jalan Khatulistiwa section, most of the road surface conditions are in moderate condition so the recommendation for improving road surface conditions is periodic maintenance on 56 segments and the other 13 segments are carried out routine maintenance. In the IRI measurement using the Roadroid application, there is a tendency to produce an IRI value that is greater than the IRI measurement using a laser profilometer, but the IRI value obtained by Roadroid tends to approach the IRI value as measured by a laser profilometer with an average percentage difference per segment of 2.91% with 2 segments that have different conditions. Based on the provisions of Pd-01-2021-BM, the IRI value test of the Roadroid has met the requirements as a class III measure of unevenness (IRI).

An integrated vision control system for the evaluation of the shape-dimensional accuracy and quality of valve forgings used in motor truck engines

The study refers to a system of vision control concerning the dimension and shape accuracy as well as quality of valve forgings assigned for motor truck engines produced in a two-operation process of forging in closed dies. The performed investigations included a complex review of the solutions regarding various methods of measuring the selected geometrical features or other parameters for different forged elements – forgings during the production process. The conducted literature analysis has showed that, due to the hard operation conditions of the forging processes, measurements of this type are very difficult and the elaborated measurement methods are often dedicated to specific forgings and forging processes. On this basis, a proprietary measuring method was developed based on an adapted industrial laser profilometer installed on a proprietary measurement station, making it possible to conduct measurements under industrial conditions, owing to the application of the elaborated construction enabling automatic collection and manipulation of the scanned forgings directly on the production line. The built system makes it possible to measure the 2 key geometrical characteristics of an exhaustion valve forging: feature A – the diameter of the outer valve head, feature B - the calotte's depth, as well as, additionally, feature C – the surface quality in the form of detection of the most frequent defect: radial scratches (cavities) on the upper surface of the disc-like forging. In the first place, measurements under laboratorial conditions were made, which were then repeated under industrial production conditions in order to determine the influence of operating conditions (like: vibrations, temperature, etc.). Next, a final verification of the constructed system was carried out for forgings measured under strictly industrial conditions (measurement of forgings collected directly from the process). The obtained results of the elaborated measurement method showed high accuracy of the proposed solution, as, compared to the results under laboratorial conditions vs. industry, the error in the case of the 2200th forging, for feature A, equalled 0.35 mm, and for feature B (for 2200th and 100th forging), it was about 0.02 mm. Further studies will focus on be the possibility of measuring the profile of the disc's transition into the leg as well as detection of defects on the forging's leg in the form of longitudinal scratches.

Dental implant surface morphology, chemical composition, and topography following double wavelength (2780/940 nm) laser irradiation. An in vitro study.

The aim of this in vitro study was to evaluate morphology alterations, chemical composition, and topography of moderately rough dental implants following double-wavelength laser irradiation. Commercial-grade titanium dental implants representing different surface characteristics (Osseospeed [OS], TiUnite [TiU], and Roxolid SLActive [RS]) were used. Laser irradiation was performed using a computer-controlled robotic device with calibrated energy/power settings and deionized water spray. Micro-, nano-morphology surface alterations, chemical composition, and surface topography (Sa , Sds , Sdr ) in the test group (laser plus water), control group A (water only), and control group B (no treatment) were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and white light laser profilometer (Interferometry). SEM-evaluation revealed minor between-group differences in micro- and nano-morphology within each implant system. Significant overall differences in surface element content were observed between the test and control group B for all implant systems (p < .05). For the test compared with control group B, statistically significantly higher oxygen content was detected for OS and RS (p < .05), a corresponding significant difference was detected for carbon for TiU (p < .05). For RS, a significantly lower content of titanium and zirconium was detected within the test group (p < .05). A significant difference in topography between test and control group B was observed for OS (Sa : p = .039 and Sdr : p = .041) with the highest roughness value for control group B. Altered chemical composition and surface topography were observed for all implant surfaces compared with untreated control following double wavelength laser irradiation. A clinical evaluation of the impact of the altered surface composition following double wavelength laser irradiation on the ability to reosseointegrate appears warranted.

3D-imaging of boulders using a solid-state 2D profilometer: case study for autonomous robotic rock breaker

Measurements of a boulder's fundamental physical properties like volume and shape can offer valuable insights for secondary breaking of boulders by a robotic rock breaker. This study analysed boulder shapes using a pulsed time-of-flight (TOF) solid-state laser profilometer. The 3D surface of boulders was reconstructed creating triangular meshes from point clouds provided by the profilometer. The main advantages of the 2D profilometer are the good measurement precision and accuracy, high speed, small size, real-time measurement capability, low weight, eye-safety, and lack of moving parts. The results indicate that a 3D map facilitates boulder diagnostics, aids in decision making, and represents a step towards a fully integrated autonomous robotic rock breaker in the mining industry. The present procedure is not only restricted to boulders, but it has also potential for other targets in industries that require precise determination of shapes for decision making.

SURFACE ROUGHNESS OF POLYAMIDE KNITTED FABRICS

Fabrics are never ideally smooth. Their texture varies between fine and coarse, quantified through the surface’s vertical deviation. Fabric roughness, or its opposite smoothness, is employed as measure of the surface texture of fabrics. In general, texture depends upon fiber properties, yarn count, yarn twist, and fabric structure and fabric design). This research aims to determine the limitations in visual perception of surface roughness in comparison to objective surface roughness measurements of low weight polyamide fabrics. Subjective evaluation is used for the visual assessment, while instrumental measurement of the properties was conducted using a noncontact laser profilometer. Subjective evaluation was conducted by a panel of forty untrained evaluators on a sample of seven polyamide knitted fabrics with different yarn count and composition. The roughness profile parameters were measured using Talysurf CLI 500 according to ISO 4827. Although the surface roughness measured as arithmetic mean deviation (Ra) and roughness through visual inspection of the fabric are correlated, instrumental measurements of roughness are more precise. Differences in the surface roughness arising from significantly different yarn structures will be observed, while those due to the knitted fabric structure are negligible in visual inspection.

Research on Generating Gear Grinding Machining Error Based on Mapping Relationship between Grinding Wheel Surface and Tooth Flank

This paper proposes a method to study the machining error when one is generating gear grinding based on the mapping relationship between the grinding wheel surface and the tooth flank. The profile of the grinding wheel after grinding is collected, and the theoretical tooth flank is derived according to a model of generating gear grinding. By comparing the normal deviation of the theoretical tooth flank with the measured tooth flank, the machining error characteristics are identified. Firstly, the mathematical model of generating gear grinding is established according to a multi-body theory and coordinate transformation. Secondly, the experiments of the lead modification for helical gear were performed on a YW7232 CNC gear grinding machine. The tooth flank twist compensation function was turned off in experiments No. 1–No. 3, and it was turned on in experiments No. 4–No. 6, while the other process parameters kept the same. Then, the corresponding theoretical tooth flank data were derived from the grinding wheel surface which were measured using the laser profilometer LJ-V7000. Finally, the machining error characteristics were obtained by analyzing the difference between the theoretical and measured tooth flank deviations. The result of this paper can provide theoretical and practical references for the improvement of the gear grinding accuracy and gear modification design.

Adoption of ASTM A956-06 Leeb hardness testing standard to rock engineering applications

The Leeb dynamic hardness test was originally developed for metallic materials and is now widely used in rock engineering and engineering geology. This study aims to fundamentally investigate the application conditions of the Leeb hardness test in rock engineering because it is a high-precision, fast, nondestructive, and portable method. Therefore, four main limitations of the Leeb method mentioned in ASTM A956-06 have been further analyzed. The important challenges, including scale effect, temperature effect, surface roughness effect, and the effect of physical properties on the Leeb method, have been studied. For this purpose, 33 rock samples with a wide range of hardness and different geology origins were used. Based on the results, the minimum thickness of the block samples of 5 cm (or volume of 500 cm3) and the length-to-diameter ratio of 1.6 on core samples were suggested. Moreover, block samples were exposed to various temperatures, including −30, 0, 20, 50, 100, and 150 °C. The results indicated that with increasing the temperature, the Leeb hardness decreased, but the trend of the Leeb hardness variations is unnoticeable. The roughness analyses using a laser profilometer indicate that the Leeb hardness of rough samples can easily be determined with high reliability using the Leeb hardness of polished samples. Also, the Leeb hardness test for rough surfaces with JRC <4 (classes 1 and 2) can be used properly and performed locally in classes 3 to 10. Finally, the statistical analyses showed that the density and porosity have reasonable effects on Leeb's hardness.