Thermal Deformation Measurement Research Articles

Thermal Deformation Measurement of the Surface Shape of a Satellite Antenna Using High-Accuracy Close-Range Photogrammetry.

To determine both the size of a satellite antenna and the thermal deformation of its surface shape, a novel high-accuracy close-range photogrammetric technique is used in this study. The method is also applied to assess the performance of the antenna in orbit. The measurement principle and solution method of close-range photogrammetry were thoroughly investigated, and a detailed measurement test scheme was developed. A thermal deformation measurement of the surface shape of a satellite antenna was then carried out. The results show that the measurement error using close-range photogrammetry was smaller than 0.04 mm, which meets the accuracy requirement. Thanks to the high accuracy, it was discovered that both the surface shape and the rib precision of the satellite antenna deteriorate with decreasing temperature. The accuracy of the surface shape and ribs was lowest when the temperature node was -60 °C. The maximum root mean square errors (RMSEs) reached 0.878 mm and 0.761 mm, respectively. This indicates that the surface shape deformation error of the antenna caused by high and low temperatures is relatively high. However, the requirement for the technical design index (RMSE ≤ 1 mm for the surface shape accuracy of the antenna) is still met. Furthermore, for temperature differences of 40 °C and 80 °C, the measured RMSEs for the surface shape deformation were 0.216 mm and 0.411 mm, respectively. Overall, the technical design indicators (RMSE ≤ 0.3 mm and RMSE ≤ 0.5 mm, respectively) for the surface shape deformation of the antennas are met.

High-Temperature DIC Deformation Measurement under High-Intensity Blackbody Radiation

During the high-speed flight of a vehicle in the atmosphere, surface friction with the air generates aerodynamic heating. The aerodynamic heating phenomenon can create extremely high temperatures near the surface. These high temperatures impact material properties and the structure of the aircraft, so thermal deformation measurement is essential in aerospace engineering. This paper revisits high-temperature deformation measurement using the digital image correlation (DIC) technique under high-intensity blackbody radiation with a precise speckle pattern fabrication and a heat haze reduction method. The effects of the speckle pattern on the DIC measurement have been thoroughly studied at room temperature, but high-temperature measurement studies have not reported such effects so far. We found that the commonly used methods to reduce the heat haze effect could produce incorrect results. Hence, we propose a new method to mitigate heat haze effects. An infrared radiation heater was employed to make an experimental setup that could heat a specimen up to 950 °C. First, we mitigated image saturation using a short-wavelength bandpass filter with blue light illumination, a standard procedure for high-temperature DIC deformation measurement. Second, we studied how to determine the proper size of the speckle pattern in a high-temperature environment. Third, we devised a reduction method for the heat haze effect. As proof of the effectiveness of our developed experimental method, we successfully measured the deformation of stainless steel 304 specimens from 25 °C to 800 °C. The results confirmed that this method can be applied to the research and development of thermal protection systems in the aerospace field.

Satellite Synthetic Aperture Radar, Multispectral, and Infrared Imagery for Assessing Bridge Deformation and Structural Health—A Case Study at the Samuel de Champlain Bridge

A space-borne remote sensing method was applied, validated, and demonstrated in a case study on the Samuel de Champlain Bridge in Montreal, Canada. High-resolution C-band radar satellite imagery was analyzed using the Persistent Scatterer Interferometric Synthetic Aperture Radar technique to derive bridge displacements and compare them against theoretical estimates. Multispectral and long-wave thermal infrared satellite imagery acquired during the InSAR observation period and historical environmental data were analyzed to provide context for the interpretation and understanding of InSAR results. Thermal deformation measurements compared well with their theoretical estimates based on known bridge geometry and ambient temperature data. Non-thermal deformation measurements gave no evidence of settlement during the 2-year monitoring period, as would normally be expected for a newly constructed bridge with its foundation on bedrock. The availability of environmental data obtained from multispectral and thermal infrared satellite imagery was found to be useful in providing context for the bridge stability assessment. Ambient temperature measurements from thermal infrared satellite imagery were found to be a suitable alternative in cases where data from in situ temperature sensors or nearby weather stations are not available or not fit for purpose. No strong correlation was found between the river conditions and bridge deformation results from the InSAR analysis; this is partly due to the fact that most of these effects act along the river flow in the north–south direction, to which the satellite sensor is not sensitive.

A DIC method for thermal micro-deformation measurement of satellite high stability composite structure in simulated space environment

In order to ensure the stability and reliability of the entire satellite and onboard equipment indicators, the satellite highly stable structure can only produce small deformation or “near zero deformation” under the space on-orbit (thermal/vacuum) environment. The effective measurement and verification of its dimensional stability indicators directly determine the success or failure of the development of highly stable satellites. This work proposes a method for measuring the thermal deformation of highly stable satellite structures based on digital image correlation, (DIC), which designs a combined methodology of the digital image correlation measurement scheme, a measurement instrument protection method, a highly uniform temperature measurement and control system in the simulated space on-orbit thermal/vacuum environment. The methodology proposed in the work makes the digital image correlation measurement system suitable for space on-orbit measurement, and verifies that the measurement system can maintain high measurement accuracy. The research results indicate that this method can effectively solve the problems of measurement field interference, high uniform temperature control, speckle measurement camera, and measurement baseline protection. The thermal stability measurement experiment of a highly stable structure of a certain satellite has been successfully completed, and it has been verified that this method can meet the effectiveness and measurement accuracy of simulating thermal deformation measurement of structures in the simulated space on-orbit thermal environment.

Measurement and Analysis of Thermal Deformation of Wireless Charger PCB due to Heat

Measurement and Analysis of Thermal Deformation of Wireless Charger PCB due to Heat

Vision-based volumetric displacement measurement with a self-illuminating target

Thermal deformation is a major source of errors in machine tool positioning. Although the volumetric measurement of thermal deformation is crucial for improving the modeling accuracy of thermal deformations, it is still challenging. This study examines the possibility of vision-based volumetric displacement measurement. A measurement method using three-dimensional (3D) reconstruction is proposed. Combining the extended intensity-fitting method with newly developed self-illuminating target having a good signal-to-noise ratio can achieve accurate position detection. The measurement accuracy of the proposed method was analyzed. A verification experiment was also conducted at a machining center.

Research on the Measurement of Thermal Deformation of Tools on High-speed Machining Centers Based on Image Processing Technology

This paper focuses on the issues of tool thermal deformation during machine preheating，designing an image-processing-based solution for measuring these tool thermal deformation, to obtain the axial thermal error of the tool as a function of preheating time.This paper uses a high-speed camera to collect images of tool thermal deformation. Using MATLAB software, rough localization of images by Canny algorithm for edge extraction. Accurately locating tool edge outlines using a sub-pixel fitted edge detection method, that is, using the least squares method to fit a tool tip arc curve. From this, the thermal deformation during tool preheating is calculated. This study will serve as a basis for the compensation of thermal errors in machine tools.

Effect of fine and coarse recycled aggregates on high-temperature behaviour and residual properties of concrete

This paper presents the results of an experimental study on the effect of recycled aggregates on concrete subjected to high temperatures. Concretes with natural aggregates (0S-0G), 30 % substitution of recycled concrete coarse aggregates and sand (30S-30G), and 100 % substitution of recycled gravel (0S-100G) were studied. The influence of recycled aggregates on the evolution of the thermophysical properties of concrete as a function of temperature when heated to 600 °C and then cooled, as well as on the temperature distribution within a cylindrical specimen was investigated. Thermal deformation measurements from 20 °C to 800 °C showed the favourable influence of the substitution of siliceous sand by recycled sand. For all concretes, residuals compressive strength and elastic modulus decrease and porosity increases with the temperature.

Time-gated active imaging digital image correlation for deformation measurement at high temperatures

We proposed a novel time-gated active imaging digital image correlation (DIC) method based on bandpass filtering and gated single-photon imaging techniques for high-temperature deformation measurement. The proposed method uses a powerful pulsed laser for illumination and then records the reflected pulsed laser light using a gated single-photon camera with an ultrashort exposure time. As a result, the received radiation light from the heated object and the ambient light can be significantly reduced to a negligible level compared with the illumination light intensity from the pulsed laser. Experiments including the varying ambient light test and thermal deformation measurement of a Ni-based alloy at around 700 °C verified the performance of the proposed method. It is observed that the established time-gated active imaging DIC system is dramatically superior to existing blue-light DIC and ultraviolet-DIC (UV-DIC) systems in preserving the image quality at high temperatures, thus showing promising application prospects in extremely challenging scenarios, such as ultra-high-temperature material testing, or thermomechanical testing of hypersonic materials and structures subjected to transient aerodynamic heating simulated by quartz lamps or an arc-heated wind tunnel.

Thermal Deformation Modeling for Phased Array Antenna Compensation Control.

Thermal compensation control can correct errors caused by the thermal deformation of phased array antenna (PAA) panels. Thermal deformation of the panel is needed to calculate the compensation value. While the PAA is working, thermal deformation is unconditional to measure, but predicting it by temperature is feasible. However, thermal deformation is also affected by other factors, such as the structural shape, assembly method, and material parameters, and it is difficult to measure these parameters of PAA because of the complex structure. In contrast, the measurement method of the temperature and thermal deformation of the PAA in the laboratory is much easier. Therefore, a comprehensive influence parameters (CIPs)-finite element method (FEM) method was proposed in this study, it can extract the influence of above parameters on thermal deformation from temperature and thermal deformation measurement data and build a thermal deformation prediction model. Experiments have verified that the CIPs-FEM can greatly reduce the difficulty of thermal deformation modeling and have a high prediction accuracy.

PREDICTION OF THERMAL GROWTH IN A HIGH-SPEED SPINDLE BY CONSIDERING THERMO-MECHANICAL BEHAVIOR

Continuous rotation of spindle bearings and motor cause thermally induced structural deformations and thermal growth, which is one of the main reasons for machining errors. A positive feedback loop between bearing preload and heat generation causes preload variations in spindle bearings. These preload variations demonstrate a nonlinear transient behavior until the gradual expansion of outer bearing rings after which the thermally induced preload variation behaves steadily. In this study, a Finite Element (FE) framework is presented for predicting steady preload variation on spindle bearings. The method involves a thermal loading model and a transient contact analysis. In the contact analysis phase bearing contact deformations (penetration and sliding) and pressure are predicted by considering contact algorithms in an FE software. A transient spindle simulation in FE is employed to predict the bearing temperature and thermal spindle growth by using the proposed method. The performance of the method is demonstrated on a spindle prototype through bearing temperature and thermal deformation measurements. Results show that the proposed method can be a useful tool for spindle design and improvements due to its promising results and speed without the need for tests.

High-throughput measurement of coefficient of thermal expansion using a high-resolution digital single-lens reflex camera and digital image correlation.

High-throughput measurement of thermal deformation and determination of coefficient of thermal expansion (CTE) using a high-resolution digital single lens reflex (DSLR) camera and digital image correlation (DIC) is described. To mitigate the mosaic effect caused by the Bayer filter of DSLR cameras, a color image pre-processing method, which adjusts the brightness and equalizes the color channels of the raw image, is carried out. In addition, a Gaussian pre-filtering step is adopted for denoising the images captured with DSLR cameras to enhance the subpixel registration accuracy. Then, by processing the recorded images using the state-of-the-art DIC algorithm, full-field displacements and strains can be determined. Compared with conventional industrial cameras, a DSLR camera offers not only portability, compactness, and economy but also much higher resolution of recorded images, allowing CTE characterization with higher throughput. Real experiments, including a verification experiment of the color image pre-processing technique, a benchmark CTE determination of Al alloy, and a high-throughput CTE determination of 15 samples of three different metals, validated the feasibility and accuracy of the proposed technique. The proposed method is cost-effective and time-saving, showing great potential in the high-throughput CTE measurement and other high-throughput strain measurement scenarios.

Accuracy Improving Deformation Measurement System for Large Components in Thermal Vacuum Using Close-Range Photogrammetry

The structure deformation of the spacecraft due to the variation of temperature in space has a significant effect on the performance and stability of the spacecraft. Therefore, a system with high accuracy to identify the deformation is proposed in this study for large components in thermal vacuum using close-range photogrammetry. A novel thermal vacuum deformation measurement platform is firstly presented to provide a space simulation chamber in where not only temperature of specimen are available from − 170 to + 140 °C, but also coordinates of measurement points of component can be efficiently measured by using close-photogrammetry. In addition, an improved deformation computation method based on coordinate optimization registration is proposed. In this method, through combining random sample consensus with singular value decomposition, partial global points whose variations are relatively small can be selected for coordinate registration. Finally, the deformation measurement for the main reflector of a Cassegrain antenna in thermal vacuum is selected as an example to validate the effectiveness of the proposed platform and method. The experimental results show that the platform and method are practical and will provide a foundation for further applications.

Research on Teaching Reform of Experimental Measurement of Temperature Field and Thermal Deformation of Machine tool

With innovation and reform proposal of intelligent manufacturing 2025 in China, the precision of machine tool is required to be higher in the field of intelligent manufacturing, and the thermal deformation of machine tools is one of the main factors affecting machining accuracy. The measurement of temperature field and thermal deformation of machine tool has become one of the most important contents in undergraduate teaching experiments in many colleges and universities. In view of the shortcomings of the traditional teaching of the experiment, which only uses some instruments for finite point measurement, an experimental teaching scheme is supplemented by vibration for full-state testing, along with a new testing technology is proposed in this paper. All of them are expected to enrich testing means, expand the students’ horizons, improve students’ ability of testing, data processing and analysis, increase students’ interest in learning, and enhance students’ comprehensive design ability of machine tool fixture. The practice shows that the experimental teaching plays a positive role in cultivating students’ knowledge mastery ability and using theoretical knowledge to solve problems, thus greatly improve the teaching effect.

Dynamic 3D measurement of thermal deformation based on geometric-constrained stereo-matching with a stereo microscopic system

In three-dimensional (3D) shape measurement applications based on absolute phase matching in fringe projection profilometry, measurement accuracy can be improved by using denser fringes under the pre-condition that the phase ambiguities can be successfully removed after phase unwrapping. In real-time measurement situations, the number of fringe patterns is limited to reduce motion-induced errors, which does, however, pose more difficulties for the absolute phase recovery of dense fringes. In this paper, we propose a stereo phase matching method that takes advantage of the high accuracy of denser fringes and the high efficiency of using only two different fringe frequencies. The phase map is divided into several sub-areas, and in each sub-area the phase is unwrapped independently. The stereo-matched pixel is selected from the distributed candidates in these sub-areas by geometric constraints. Experimental results show that only five patterns are needed to perform a high-accuracy real-time 3D measurement of the thermally induced deformation of the sample under different heating temperatures based on a telecentric stereo microscopic system.

Nanometer-order thermal deformation measurement by a calibrated phase-shifting digital holography system.

A thermal deformation measurement system based on calibrated phase-shifting digital holography is proposed. Two synchronized ordinary CMOS cameras are used in the calibrated phase-shifting digital holography system. One is to record the holograms including the object information, and the other is to record the interference fringes to evaluate phase-shifting errors. The calibrated phase-shifting digital holography can provide the high quality reconstructed images which are applied to calculate the thermal deformation of the object. Meanwhile, the thermal images of the object at different temperatures are recorded by a thermal camera. Nanometer-order thermal deformation measurement of an electronic device is achieved in a real experiment. Our measurement system could be useful for electric packaging materials development or the system design.

Low-cost, portable, robust and high-resolution single-camera stereo-DIC system and its application in high-temperature deformation measurements

A low-cost, portable, robust and high-resolution single-camera stereo-digital image correlation (stereo-DIC) system for accurate surface three-dimensional (3D) shape and deformation measurements is described. This system adopts a single consumer-grade high-resolution digital Single Lens Reflex (SLR) camera and a four-mirror adaptor, rather than two synchronized industrial digital cameras, for stereo image acquisition. In addition, monochromatic blue light illumination and coupled bandpass filter imaging are integrated to ensure the robustness of the system against ambient light variations. In contrast to conventional binocular stereo-DIC systems, the developed pseudo-stereo-DIC system offers the advantages of low cost, portability, robustness against ambient light variations, and high resolution. The accuracy and precision of the developed single SLR camera-based stereo-DIC system were validated by measuring the 3D shape of a stationary sphere along with in-plane and out-of-plane displacements of a translated planar plate. Application of the established system to thermal deformation measurement of an alumina ceramic plate and a stainless-steel plate subjected to radiation heating was also demonstrated.

Measurement of thermal deformation of magnetic alloy cores of radio frequency cavities in 3-GeV rapid-cycling synchrotron of Japan proton accelerator research complex

Magnetic alloy cores loaded in radio frequency cavities are employed to achieve a high field gradient in the 3-GeV Rapid-Cycling Synchrotron of the Japan Proton Accelerator Research Complex. We use three core-types, which were manufactured in three different processes. Buckling occurred in some cores of only one of the three core types. In order to find out the mechanism of buckling, we measured thermal deformations of the two core types, which had not buckled and the core types, which had buckled, while changing their temperatures by RF heating in air. Furthermore, we calculated the thermal stress using the results of the experiments. These experiments yielded that there was no remarkable difference in the strength of thermal stress between the core types, which had not buckled, and the core types, which had buckled; however, that there was a clear difference in the behavior of thermal deformations. The local deformations appeared, when a certain temperature was exceeded, and accelerated with temperature rise in the buckled core types. This was not seen with core types that did not show the buckling problem. We conclude that the repetition of these catastrophic and local deformations, which are accelerated with the temperature rises, lead to the buckling.

Measurement method of multi scale thermal deformation inhomogeneity in CFRP using in situ FE-SEM observations

The measurement of nano scale thermal deformation and strain inhomogeneity in the transverse direction in carbon fiber-reinformed polmer (CFRP) in the temperature range 170–370K has been carried out by in-situ Field Emission Scanning Electron Microscopy (FE-SEM) observation using a heating and cooling stage in the FE-SEM chamber. A grid pattern and also random patterns were drawn on the polished sample surface at different length scales. The electron moiré method was applied to measure the macroscopic deformation and the digital imaging correlation method was applied to measure the nano-scale deformation around the fiber/matrix interface. The strain inhomogeneity of the pitch-based carbon fiber in the transverse direction and the debonding at the interface between fiber and matrix has been evaluated quantitatively.

Failure and stress analysis of through-aluminum-nitride-via substrates during thermal reliability tests for high power LED applications

The objective of this study is to evaluate the reliability of through-aluminum-nitride-via (TAV) substrate by comparing those experimental results with the finite element simulation associated with measurements of aluminum nitride (AlN) strength and the thermal deformation of Cu/AlN bi-material plate. Two reliability tests for high-power LED (Light emitting diode) applications are used in this study: one is a thermal shock test from −40°C to 125°C, the other is a pressure cook test. Also, the strength of AlN material is measured by using three-point bending test and point load test. The reliability results show that TAV substrates with thicker Cu films have delamination and cracks after the thermal shock test, but there are no failure being found after the pressure cook test. The determined strengths of AlN material are 350MPa and 650MPa from three-point bending test and point load test, respectively. The measurement of thermal deformation shows that the bi-material plate has residual-stress change after the solder reflow process, also indicating that a linear finite element model with the stress-free temperature at 80°C can reasonably represent the stress state of the thermal shock test from −40°C to 125°C without considering Cu nonlinear effect. The further results of the finite element simulation associated with strength data of AlN material have successfully described those of the reliability test.