Temperature-induced Deformation Research Articles

Thermal-deformation behaviors of the primary sealants in double, triple, and multi glazed insulating glass units

Polyisobutylene (PIB), commonly used as the primary sealant of double, triple, and multi glazed insulating glass units (IGUs), provides the key moisture barrier function and determines the expected lifespan of the IGUs and even the entire glass curtain wall systems (GCWSs). Slipping and debonding of the PIB, caused by temperature changes, have resulted in numerous instances of premature failure of building envelopes. However, available research is inadequate in accurately evaluating the service environment of IGUs and thermal-deformation behaviors of this energy-saving building material. This paper presented a simplified method for analyzing the thermal environment of IGUs, considering outdoor air temperature, solar radiation, wind speed, and angle to the horizontal. A numerical modeling method was proposed and validated with the heat transfer tests. Three finite element (FE) models were built and utilized for the precise analysis of temperature-induced deformations of double, tripled, and quadruple glazed IGUs. Simplified calculation formulas for the maximum thermal deformation of PIB in the X and Y directions under different temperature conditions were obtained, taking a new concept “cavity-to-pane ratio” into consideration. Finally, the relationship between the PIB’s temperature-induced deformation and its probability was proposed. The results show that the IGUs in Beijing suffer more than 22 % of their time in harsh service conditions where the difference between indoor and outdoor temperatures exceeds 20 °C. For DIGUs, the maximum temperature-induced deformations of the PIB in X (along the short side of the panel) and Y (along the long side of the panel) directions are 0.142 and 0.214 mm, respectively, corresponding to shear strains of 28.4 % and 42.8 % for the PIB with a thickness of only 0.5 mm. For TIGUs, the maximum deformations increase to 0.159 and 0.239 mm, corresponding to shear strains of 31.8 % and 47.8 %. For QIGUs and the other multi-glazed IGUs, these values can increase to 36.8 % and 55.4 % or more. The methodology proposed in this paper aims to lay the groundwork for further addressing premature failure issues and optimizing edge bond constructions of multi-glazed IGUs.

Deep learning-based minute-scale digital prediction model for temperature induced deflection of a multi-tower double-layer steel truss bridge

Bridge deflection serves as a vital and intuitive index for the evaluation of bridge safety. Temperature load has the greatest influence on the bridge deformation and studies on the temperature-induced deformation prediction of long-span bridge are in limited numbers. A digital prediction model based on deep learning in minute scale is established to study the bridge deflection caused by temperature. The wavelet transform (WT) is adopted to filter the high-frequency signals of the original deflection caused by the related load factors. Three different networks, long short-term memory (LSTM), bidirectional LSTM (Bi-LSTM), and Transformer variant, are studied and compared in the prediction process. Two different learning strategies considering different input data are also considered to optimize the prediction performance. The proposed prediction model is applied to the temperature induced deflection prediction of a multi-tower double-layer steel truss bridge. The results show that strategy A, which employs temperature time series data as input, is less effective than strategy B. Incorporating both temperature and deflection data as inputs is essential for predicting temperature-induced deflections. Moreover, the Transformer-variant network generally exhibits superior prediction performance compared to the LSTM and Bi-LSTM. The self-attention mechanism of the Transformer allows it to focus on key historical temperature points, thereby enhancing prediction accuracy.

Thermochromism and thermal crystal structure evolution of YIn0.9Mn0.1O3

YIn1-x Mn x O3 is a newly discovered inorganic blue pigment whose vivid blue color results from MnO5 trigonal bipyramidal (TBP) polyhedra. Recently, it has been reported that commercial YIn1-x Mn x O3 powders exhibit a temperature-induced color change, i.e. thermochromism. In this study, we investigate the thermochromism and temperature-induced crystal structure evolution of synthetic YIn0.9Mn0.1O3 powders. We observe that a vivid blue color at RT gradually changed to a dark blue color with increasing temperature. This thermochromism is mainly attributed to a broadening of optical absorption bands in the visible and UV regions, and can also be contributed to by an enhancement of the UV absorption. Our crystal structure analysis using powder synchrotron X-ray diffraction data not only confirms the thermal expansion and enhanced thermal vibrations of oxygen, but also reveals a temperature-induced deformation of the TBP polyhedra. Based on these results, we discuss a possible mechanism for the thermochromism of the YIn0.9Mn0.1O3 system.

Mechanical behavior of longitudinally continuous slab tracks reinforced by adhesive anchors under nonlinear temperature load

Adhesive anchors have been widely used as a post-reinforcement measure to strengthen longitudinally continuous slab tracks. However, the mechanical behavior of the longitudinally continuous slab tracks reinforced by adhesive anchors under nonlinear temperature load has not been thoroughly investigated. Therefore, this paper was motivated to conduct experimental and numerical investigation on the temperature-induced deformation and damage of the reinforced track. Firstly, experimental tests were carried out to investigate the influence of the borehole conditions on the bond properties of post-installed adhesive anchors. Next, the bond-slip relationships between anchors and concrete were established for anchors in various borehole conditions. Then, a novel finite element model of the reinforced track incorporating a nonlinear cohesive zone model of structural interfaces was developed and validated by filed monitoring data. Finally, the effects of borehole conditions and number of invalid anchors on the deformation and damage behavior of the reinforced track under nonlinear temperature load were systematically studied. Results show: (1) The cubic compressive strength grade of concrete has a significant effect on the bond-slip curves between concrete and anchors of the longitudinally continuous slab track. (2) Wet boreholes and uncleaned boreholes would reduce elastic stiffness and ultimate bond strength between anchors and concrete by 11–37% respectively, compared with dry and cleaned boreholes. (3) The maximum vertical displacement of slabs could increase by 7% and 4% if the boreholes are wet and uncleaned respectively. (4) The interface at the center of slab end near damaged joint will not fail for the track with 1 or 2 invalid anchors when the temperature reaches its highest. However, interface debonding will occur with a temperature rise of 34.6 ℃ if there are 3 invalid anchors.

In Situ Dilatometry Measurements of Deformation of Microporous Carbon Induced by Temperature and Carbon Dioxide Adsorption under High Pressures

Adsorption-based carbon dioxide capture, utilization, and storage technologies aim to mitigate the accumulation of anthropogenic greenhouse gases that cause climate change. It is assumed that porous carbons as adsorbents are able to demonstrate the effectiveness of these technologies over a wide range of temperatures and pressures. The present study aimed to investigate the temperature-induced changes in the dimensions of the microporous carbon adsorbent Sorbonorit 4, as well as the carbon dioxide adsorption, by using in situ dilatometry. The nonmonotonic changes in the dimensions of Sorbonorit 4 under vacuum were found with increasing temperature from 213 to 573 K. At T > 300 K, the thermal linear expansion coefficient of Sorbonorit 4 exceeded that of a graphite crystal, reaching 5 × 10−5 K at 573 K. The CO2 adsorption onto Sorbonorit 4 gave rise to its contraction at low temperatures and pressures or to its expansion at high temperatures over the entire pressure range. An inversion of the temperature dependence of the adsorption-induced deformation (AID) of Sorbonorit-4 was observed. The AID of Sorbonorit-4 and differential isosteric heat of CO2 adsorption plotted as a function of carbon dioxide uptake varied within the same intervals of adsorption values, reflecting the changes in the state of adsorbed molecules caused by contributions from adsorbate–adsorbent and adsorbate–adsorbate interactions. A simple model of nanoporous carbon adsorbents as randomly oriented nanocrystallites interconnected by a disordered carbon phase is proposed to represent the adsorption- and temperature-induced deformation of nanocrystallites with the macroscopic deformation of the adsorbent granules.

Simultaneous 3D measurement for infrared chips with speckle interferometry

Temperature-induced deformation in the infrared detector chip is a key index for evaluating image aberration and stress concentration. Development of an evaluation means for simultaneous characterization of 3D deformation is of great interest to engineering societies. In this study, an integrated device based on speckle interferometry has been developed for evaluation of the three-dimensional (3D) deformation of the infrared detector chip with variations of temperature. With the use of a 3CCD color camera and a group of optical fibers, the 3D displacement components of the detector surface are measured simultaneously during the cooling process. A temporal phase shifting scheme based on GPU parallel computing has been proposed to enable quantitatively real-time 3D measurement in three image layers at a rate of 20 fps. The integrated device has been validated with a benchmark test. The experimental results show a good agreement with the theoretical solution validating the stability and accuracy of the experimental device. The developed speckle interferometry device provides an accurate means in simultaneously evaluating the 3D deformation of the infrared detector chip due to temperature variations.

GRNN Prediction Model for Temperature-Induced Deformation of CRTS II Unballasted Slab Track

The General Regression Neural Network (GRNN) is one of the algorithms of artificial neural networks (ANN) that receives much attention in prediction applications. This research used the GRNN to predict the temperatureinduced deformation of unballasted track structures based on experimental data considering external weather conditions, such as sunshine duration, rain conditions, daily maximum temperature, daily minimum temperature, and daily average wind speed. The GRNN network predicts the average absolute error of the prediction results (0.0318 ℃), the maximum absolute error (1.7729 ℃), and the GRNN prediction sample mean squared error (0.070701). The average relative error is 0.32%. The finding of this study shows that the GRNN prediction method has good accuracy and robustness. Furthermore, it can promote the research of unballasted track temperature fields that are related to concrete structures.

Volume deformation of steam-cured concrete with fly ash during and after steam curing

Steam-cured concrete presents high compressive strength at an early age. However, understanding regarding temperature-induced deformation development in steam–cured concrete with fly ash is limited. In the present research, the volume deformation of fly ash concrete experienced steam curing stage at an early age has been carried out. Volume deformation of concrete without fly ash is also studied as a comparison. In order to obtain the in situ property changes of steam-cured concrete, a strain-temperature-humidity integrated acquisition system was used to continuously record the interior strain, temperature, and humidity evolutions of the sample. The test results show that the autogenous shrinkage occurs at the constant temperature stage of steam curing, and the shrinkage after steam curing is mainly because of the drying effect. The addition of fly ash can increase the development of shrinkage in steam curing, but it is beneficial to shrinkage after steam curing. And the hydration degree prediction development model of steam-cured cement paste is proposed. Finally, a micromechanical model is proposed based on the capillary tension produced by pores, using interior humidity and hydration degree as the driving parameters, which decently predicts the total shrinkage and autogenous shrinkage of concrete specimens after steam curing.

Peculiarities of Thermodynamic Behaviors of Xenon Adsorption on the Activated Carbon Prepared from Silicon Carbide.

An activated carbon prepared from silicon carbide by thermochemical synthesis and designated as SiC-AC was studied as an adsorbent for xenon. The examination of textural properties of the SiC-AC adsorbent by nitrogen vapor adsorption measurements at 77 K, powder X-ray diffraction, and scanning electron microscopy revealed a relatively homogeneous microporous structure, a low content of heteroatoms, and an absence of evident transport macropores. The study of xenon adsorption and adsorption-induced deformation of the Si-AC adsorbent over the temperature range of 178 to 393 K and pressures up to 6 MPa disclosed the contraction of the material up to −0.01%, followed by its expansion up to 0.49%. The data on temperature-induced deformation of Si-AC measured within the 260 to 575 K range was approximated by a linear function with a thermal expansion factor of (3 ± 0.15) × 10−6 K−1. These findings of the SiC-AC non-inertness taken together with the non-ideality of an equilibrium xenon gaseous phase allowed us to make accurate calculations of the differential isosteric heats of adsorption, entropy, enthalpy, and heat capacity of the Xe/SiC-AC adsorption system from the experimental adsorption data over the temperature range from 178 to 393 K and pressures up to 6 MPa. The variations in the thermodynamic state functions of the Xe/SiC-AC adsorption system with temperature and amount of adsorbed Xe were attributed to the transitions in the state of the adsorbate in the micropores of SiC-AC from the bound state near the high-energy adsorption sites to the molecular associates.

Analytical formulas of thermal deformation of suspension bridges

Deformation of a long-span suspension bridge is mainly caused by ambient temperature changes. The temperature-induced deformation of a bridge is usually calculated using complex three-dimensional finite element analysis, the mechanism of which is often unclear. In this study, we derive general, succinct analytical formulas of the thermal deformation of three-span suspension bridges. The deformation of different components is unified into a one-dimensional thermal expansion formula (δL=LEθ·δT) by introducing an equivalent length LE. The sag effect of side-span cables is characterized by the modification coefficients, which demonstrate that the neglect of the sag effect overestimates the thermal deformation. Furthermore, the thermal deformation of the main- and side-span cables and towers is found to interact with each other as a result of the cable tension changes with varying temperature. The analytical formulas are validated using eight long-span suspension bridges including the Akashi Kaikyo bridge, the longest main-span suspension bridge in the world. The closed-form solutions herein also apply to the self-anchored suspension bridges.

Temperature deformation characteristics of acrylic windows used for tide embankments

<abstract> <p>Tide-embankment walls protecting coastal roads frequently contain numerous windows so that pedestrians and drivers can view the scenery without experiencing reduced sunlight. Tide-embankment windows must withstand extreme climatic conditions. However, the effects of temperature extremes on acrylic boards have rarely been studied. This paper proposes a simple method for constructing a high-temperature environment and a method for measuring strain on an acrylic plate. The deformation and strain of a 40-mm-thick acrylic tide-embankment window were determined experimentally and numerically in this study in a high-temperature environment, obtaining similar results; additionally, the numerical method was subsequently used to simulate a low-temperature environment. Because thermal conductivity was low, the internal temperature of the thick acrylic board did not immediately change with the temperature of the surface, and thermal expansion and contraction of the board were restrained. Temperature-induced deformation effects were low across the entire range of temperatures and heating rates recorded in coastal Japan.</p> </abstract>

Thermo-Mechanically Trained Shape Memory Alloy for Temperature Recording With Visual Readout

Economical sensing and recording of temperature are important in the transportation and management of sensitive goods such as medicine. Existing approaches measure the entire temperature profile using electronic devices running on a continuous power source. This letter presents a simple, intelligent, and battery-free solution for capturing informative temperature events using the natural thermo-mechanical state of a shape memory alloy (SMA). This approach utilizes the temperature-induced irreversible mechanical deformation of the SMA as a natural way to capture the temperature history without the need for electronic data logging. In this letter, a two-way SMA-based sensor is used to record both high and low temperature peak events. The reading utilizes a smartphone to visualize and quantify temperature-induced deformation for monitoring. Detailed design and experimental studies have been performed to validate the proposed approach.

Analysis of temperature-induced spectral drift in the solar spectrometer driven by leadscrew and bar mechanism

A solar spectrometer is designed and developed, which uses a leadscrew and bar mechanism as the wavelength scanning mechanism, to achieve the accurate measurement of the solar spectrum in 170 nm–350 nm range. When measuring the standard spectrum of mercury lamp under laboratory conditions, there is a spectral drift due to temperature-induced deformation of the wavelength scanning mechanism. By using the finite element analysis method, the temperature sensitivity of each component in mechanism is analyzed. And then the linear superposition relationship between temperature rise and deformation is determined. Combined with the working principle of wavelength scanning mechanism, the corresponding relationship between temperature change and spectral drift is deduced.Spectral scanning and temperature monitoring were carried out simultaneously in instrument test to acquire temperature data of the wavelength scanning mechanism as it driving the gratings. Spectral drift was estimated according to the temperature variation and the maximum deviation between the predicted wavelength drift and the measured wavelength drift is 0.0016 nm, which is 6% of the measured wavelength. The experiment data validate the theoretical analysis results. The relationship between temperature change and spectral drift provides a theoretical reference for the correction of the measurement results and the thermal control of the instrument.

Analysis of temperature-induced deformation and stress distribution of long-span concrete truss combination arch bridge based on bridge health monitoring data and finite element simulation

Through decades of operation, deformation fluctuation becomes a central problem affecting the normal operating of concrete truss combination arch bridge. In order to clarify the mechanism of temperature-induced deformation and its impact on structural stress distribution, this article reports on the temperature distribution and its effect on the deformation of concrete truss combination arch bridge based on bridge health monitoring on a proto bridge with 138 m main span. The temperature distribution and deformation characteristics of the bridge structure in deep valley area are studied. Both of the daily and yearly temperature variation and structural deformation are studied based on bridge health monitoring. Using the outcome of monitoring data, three-dimensional solid finite element models are established to analyze the mechanism of temperature-induced deformation of the whole bridge under different temperature fields. The influence of temperature-induced effect is discussed on local damage based on the damage observation of the background bridge. The outcome of comparisons with field observation validates the analysis results. The relevant monitoring and simulation result can be referenced for the design and evaluation of similar bridges.

Mechanical Characteristics and Failure Mode of Asphalt Concrete for Ballastless Track Substructure Based on In Situ Tests

Asphalt concrete paved on the surface of a roadbed as a ballastless track substructure has an excellent waterproofing and vibration attenuation performance. However, the mechanical characteristics and the failure mode of this structure under the actions of a cyclic train load and ambient air temperature changes are still unclear. Therefore, a test section of an asphalt concrete substructure was constructed based on a high-speed railway ballastless track project in north China. In situ forced vibration tests and temperature-induced deformation monitoring tests were performed to investigate the mechanical responses of the asphalt concrete, respectively. Test results show that the bottom of the asphalt concrete layer is in the tensile state under the action of the cyclic train load. The surface of the asphalt concrete in contact with the base plate is subjected to tensile stress near the expansion joint under the action of the negative temperature gradient. Changes in the ambient temperature lead to more significant mechanical responses of the asphalt concrete substructure than the cyclic train load, especially near the expansion joint of the base plate. Therefore, the passive tensile failure mode may occur near the expansion joint of the base plate. However, it has also proved that setting isolation layers under the base plate near the expansion joint is an effective method to significantly reduce responses near the expansion joint in this research.

Analytical solution to temperature-induced deformation of suspension bridges

Varying ambient temperature may cause significant deformation of long-span suspension bridges. This study investigates the mechanisms of the temperature-induced mid-span deflection and tower-top horizontal displacement of suspension bridges, and formulates the general analytical solutions to the thermal responses of ground-anchored suspension bridges. The temperature-induced mid-span deflection can be determined from the superposition of deflections caused by each of the separate temperature changes of the main-span cable, side-span cables, and towers, while the tower-top horizontal displacement is a combination of the thermal effects of the side-span cables and towers. It is found that the cable temperature plays the dominant role in the mid-span deflection and tower-top horizontal displacement. Moreover, the temperature effective length is proposed and a unified formula of the temperature-induced bridge responses is obtained. The accuracy of the proposed formulas is verified through the field monitoring data of the 2132-m-long Tsing Ma Bridge at Hong Kong. The present study not only provides a simple, general, and unified analytical solution to the temperature-induced deformation of long-span suspension bridges, but also assists engineers in understanding the mechanisms of thermal behaviours of such bridges.

Identification of Temperature-Induced Deformation for HSR Slab Track Using Track Geometry Measurement Data.

Slab track is widely used in many newly built high-speed rail (HSR) lines as it offers many advantages over ballasted tracks. However, in actual operation, slab tracks are subjected to operational and environmental factors, and structural damages are frequently reported. One of the most critical problems is temperature-induced slab-warping deformation (SWD) which can jeopardize the safety of train operation. This paper proposes an automatic slab deformation detection method in light of the track geometry measurement data, which are collected by high-speed track geometry car (HSTGC). The characteristic of track vertical irregularity is first analyzed in both time and frequency domain, and the feature of slab-warping phenomenon is observed. To quantify the severity of SWD, a slab-warping index (SWI) is established based on warping-sensitive feature extraction using discrete wavelet transform (DWT). The performance of the proposed algorithm is verified against visual inspection recorded on four sections of China HSR line, which are constructed with the China Railway Track System II (CRTSII) slab track. The results show that among the 24,806 slabs being assessed, over 94% of the slabs with warping deformation can be successfully identified by the proposed detection method. This study is expected to provide guidance for efficiently detecting and locating slab track defects, taking advantage of the massive track inspection data.

Relationship of deformation mode with strain-dependent shear transformation zone size in Cu-Zr metallic glasses using molecular dynamics simulations

Tensile behaviors of a Cu64Zr36 metallic glass (MG) at different deformation temperature and the strain-dependent average shear transformation zone (STZ) size in four Cu-Zr-based MG systems, have been investigated by molecular dynamics simulations. With increasing temperature, the transition from the localized deformation to the non-localized deformation indeed occurs in Cu64Zr36 MG. Within the condition applied here, the critical temperature is estimated to be 195±5K. The criterion for the temperature-induced deformation mode transition, was suggested, i.e., the competition between the elastic-energy density stored and the energy density needed for forming one mature shear band in MGs. We further reveal that for localized deformation in all studied cases, the average STZ size remains almost unchanged at strain larger than 14% while for non-localized deformation cases, after about 14% strain, the average STZ size continuously increases with strain up to 20% strain. This feature could be used to distinguish different deformation modes in MGs.

Development of a coupled thermo-hydro-mechanical double structure model for expansive soils

In this paper, development of a thermo-hydro-mechanical model for expansive soils including double structure is described. The model is based on hypoplastic model by Masin [6], in which the hydro-mechanical coupling is considered at each of the two structural levels. The model also includes separate effective stress definitions and water retention curves for the two levels of structure. In the proposed model, an approach by Masin and Khalili [8] to include thermal effects into hypoplastic models is followed. This is combined with temperature-dependent water retention curve of macrostructure, temperature-induced deformation of microstructure and an enhanced double-structure coupling law. Good predictions of the model are demonstrated by comparing the model simulations with experimental data on MX80 bentonites taken over from literature.

Microengineered smart material probes to measure local 3D tissue stiffness in situ

Event Abstract Back to Event Microengineered smart material probes to measure local 3D tissue stiffness in situ Katherine Macdonald1, Wontae Lee1, Richard L. Leask1, 2 and Christopher Moraes1 1 McGill University, Chemical Engineering, Canada 2 Montreal Heart Institute, Canada Introduction: The stiffness of the extracellular matrix influences various cellular functions including cell development and differentiation[1]. The extracellular matrix can be remodelled by cells, an important process in disease progression[2]. Current techniques to measure extracellular matrix stiffness are limited to bulk measurements which cannot resolve local variations within a tissue, or are limited to two-dimensional surface measurements via AFM. These techniques are often destructive and limited to measurement of stiffness in a single direction, which does not capture the mechanical complexity of biological systems. Here, we develop distributable, biocompatible, microscale sensors that can be embedded in cell-laden tissues to monitor local mechanical stiffness. N-isopropylacrylamide (NIPAAm) hydrogels exhibit a significant change in shape when cooled below the lower critical solution temperature of 32oC[3]. However, the force stroke of this expansion is small and poorly defined. We characterized these small forces by monitoring temperature-induced deformation of embedded microgels in stiffness-tunable hydrogel matrices (Fig. 1), and developed a mechanosensor to monitor local mechanical properties in live tissues with high spatial and temporal resolution. Materials and Methods: pNIPAAm hydrogel beads were synthesized by free-radical polymerization in an oil/water two-phase system using established protocols[3]. A functionalized fluorescent molecule was incorporated into the hydrogel polymer backbone to enable optical measurement of bead sizes when embedded within engineered tissues. pNIPAAm beads were then embedded in polyacrylamide hydrogel matrices, and fluorescent microscopy was used to measure differences in hydrogel size as a function of temperature. Results and Discussion: When pNIPAAm hydrogel beads were cooled from 37oC to room temperature, the hydrogel beads expanded in the matrix, (Fig. 1). Expansion of the hydrogel beads was limited by the stiffness of the surrounding matrix, (Fig. 2C), and the concentration of NIPAAm and BIS, (Fig. 2B). The hydrogel beads showed a greater expansion with increasing concentration of NIPAAm and decreasing concentration of crosslinking agents. A greater expansion provides greater sensitivity in measuring stiffness. This mechanosensor provides high sensitivity in measuring the stiffness of matrices below 1 kPa, with a significant reduction in sensitivity in stiffer matrices, (Fig. 2C). Conclusion: Temperature-sensitive hydrogel smart material microbeads are able to exert sufficient forces to deform soft 3D matrices. This approach is hence extremely promising for mapping tissue mechanics by temporarily reducing the culture temperature, and monitoring bead deformation. The change in shape that results from the cooling of these hydrogel beads is reversible, allowing repeated measurements to be made from a single sensor. In addition, monitoring bead shape in addition to size may provide unique insights into anisotropic stiffness changes within 3D matrices. Natural Sciences and Engineering Research Council of Canada Discovery Grant; Natural Sciences and Engineering Research Council of Canada Undergraduate Student Research Award; Province of Quebec Fonds Nature et Technologies New Investigator award