Thermal Test Research Articles

The effect of changing the combustion chamber head structure on turbine blades under thermal shock test

When the high-pressure turbine guide blade works in the aero-engine, it is in the complex gas-heat environment of the combustion chamber and the turbine. The temperature distribution and strength of the blade affect the reliability and life of the aero-engine. In order to more accurately analyze the complex flow field aero-thermal parameters between the aero-engine combustion chamber and the turbine, this paper considers the influence of the non-uniform aero-thermal parameters of the combustion chamber outlet on the turbine. Taking the first-stage guide vane of an aero-engine turbine as the research object, the high and low temperature cycle thermal shock test was carried out to obtain the crack location and strength of the turbine guide vane, which provided a certain reference for improving the design of the turbine guide vane. Through the test, it is found that after 750 thermal shock cycles, fatigue cracks appear in four concentrated areas of the blade, which are distributed in the leading edge and trailing edge of the blade respectively. This shows that the temperature at the leading edge and trailing edge of the blade is higher, the heat load is higher, and the risk of damage and ablation is also the highest. Based on the experiment, the cross-component model of the combustion chamber and the blade is established. On this basis, four kinds of swirler structures at the head of the combustion chamber are designed. ANSYS FLUENT software is used to study the unsteady parameters such as the surface temperature of the guide vane under the influence of strong swirling flow. The numerical results show that when the rotation direction of the cyclone is counterclockwise, the temperature of the guide vane wall is more uniform. Compared with the clockwise rotation of the cyclone, the temperature is reduced by about 5 %, and the installation angle of the 50° cyclone blade is better than the installation angle of the 45° blade.

Ultra‐Stable and Bright Pure‐Red Perovskite Nanocrystals for Backlit Displays

AbstractMetal halide perovskite nanocrystals (NCs) have emerged as an alternative to conventional phosphors for wide color gamut displays. However, the issues of poor stability and low emission efficiency of pure‐red CsPbBrxI3‐x NCs set an obstacle to their practical application. Herein, the synergistic effect of Mn doping and mesoporous SiO2 sealing is reported through in situ formation of Mn‐doped NCs into mesoporous SiO2 nanospheres (MnNCs@SiO2) to structurally and spatially stabilize the perovskite NCs for bright and stable pure‐red emitter. The large bonding energy of Mn‐halogen effectively suppresses the halide vacancy defects, prompting the highest photoluminescence quantum yield (PLQY) up to 84% (634 nm) among the pure‐red composite analogs. More importantly, the nanocrystal structure stability is fundamentally improved by the enhanced formation energy with Mn doping, together with the spatial isolation by SiO2 nanospheres. The MnNCs@SiO2 films exhibit impressive stabilities against high‐temperature heating, thermal cycle test, UV irradiation, water, and acid/alkali erosion, representing one of the most stable pure‐red perovskite emitters. By integrating fabricated all‐perovskite CsPbX3 single color conversion film into the liquid crystal display (LCD) modules, a wide color gamut of 128% of NTSC is achieved, enabling an excellent color rendition for high‐saturation object colors toward practical applications.

The Thermal Energy Storage Characteristics of Oleic Acid Modified ZnO‐Decorated Polymer Matrix‐Supported Composite Phase Change Materials: Synthesis and Characterization

AbstractIn this study, modified nano zinc oxide (ZnO)‐reinforced polymer‐supported novel thermally enhanced form‐stable composite phase change materials (PCMs) are presented, which are prepared via water in oil emulsion polymerization and following impregnation process steps. First, ZnO nanoparticles are modified with oleic acid (OA) to obtain lipophilic structures for emulsion stability, which are designed to take a role as a heat transfer activator. To ensure the shape stabilization of n‐hexadecane used as organic PCM, polymeric support materials are synthesized in the presence of modified ZnO nanoparticles (ZnO@OA). The polymeric frameworks exhibit open porous morphology, and the thermal stability of the support matrix improves with the addition of ZnO nanofiller. In the second step, composite PCMs are prepared by incorporation of n‐hexadecane with the solvent‐assisted vacuum impregnation method into polymer composites. The 1.0% ZnO@OA incorporated composite PCM has the highest incorporation ratio and exhibits a thermal storage capability (η) of 100%. According to the T‐history and thermal conductivity tests, it is observed that the heat conduction rate is enhanced with the addition of ZnO@OA nanofiller. The conclusion is that the obtained ZnO@OA integrated composite PCMs have a remarkable potential for latent heat storage applications requiring low temperature in the range of 5–25 °C.

Experimental and numerical simulation studies of electrical resistance of cementitious materials under varying temperature history

Many in-service concrete structures are normally exposed to varying temperature condition. The time-dependent and non-uniform temperature distribution in concrete structures could affect the accurate assessment of their electrical properties. Therefore, the influences of temperature change over time and the spatial variation in temperature on the measured electrical resistance of cementitious materials are still in need of investigation. The coupled thermal-electrical responses of two types of cementitious materials under varying temperature history were investigated by a series of thermal and electrical tests in this study. Then a coupled thermal-electrical finite element (FE) model was developed to simulate the coupled thermal-electrical responses. The results show that the input direct current has a minor effect on the measured electrical resistance by embedded four-probe method and the specimen temperature when it is no greater than 3 mA. The relationship between the measured temperature at 10-mm depth of the specimen and the apparent resistance is well captured by a linear equation. The coupled thermal-electrical finite element model can predict well the developments of specimen temperature and apparent electrical resistance under varying temperature history. The FE results reveal that the non-uniform temperature variation results in the redistribution of electrical current within the tested specimen. However, electrical field between the two inner electrodes is always uniform when the embedded four-probe method is used, which is not affected by the non-uniform temperature variation.

A new approach for heat transfer coefficient determination in triply periodic minimal surface-based heat exchangers

The development of additive manufacturing offers increasing opportunities in heat transfer. A wider range of materials is used in the 3D printing process of heat exchangers based on the Triply Periodic Minimal Surface. Due to the complexity of these structures, it is difficult to precisely determine the values describing the heat transfer process in these devices. One of the parameters describing the heat transfer process in heat exchangers is the heat transfer coefficient. This study describes a new method for determining the heat transfer coefficient in a heat exchanger based on a gyroidal lattice. The proposed new method allows for determining the heat transfer coefficient values without interfering with the internal space of the compact heat exchanger. The developed formula can be used in the indirect method of determining the value of the heat transfer coefficient in two-phase flow with boiling or condensation of the working medium. The thermal tests were carried out in the range of working flow rates 4–24 kg/h; the media temperature was 20 and 50 °C, the heat flux was from 0.1 to 0.4 kW. Tests were conducted for laminar flow in the 20 < Re < 200 range.

Effect of Annealing Temperature on Microstructure and Properties of DH Steel and Optimization of Hole Expansion Property

In this article, DH steel containing Nb and Nb-Cu above 1000 MPa was designed, and its phase transformation law was analyzed through thermal expansion tests. The influence of annealing temperature on the microstructure and properties of DH steel was studied using a continuous annealing simulation testing machine, SEM, and tensile testing machine. The results showed that under a continuous annealing process, the test steel is composed of ferrite, martensite, a small amount of bainite, and residual austenite. The tensile strength decreases with the increase in annealing temperature, Cu element is dissolved in the matrix which produces solid solution strengthening and results in an increase in the strength of Cu-bearing test steel. Finally, 1180 MPa grade DH steel with excellent comprehensive properties was obtained at an annealing temperature of 840 °C and an overaging temperature of 340 °C. The expansion performance of the experimental steel was studied and optimized. Under the step heating annealing process, the experimental steel is composed of tempered martensite, ferrite, and residual austenite, with smaller differences in hardness between different phases, lower average dislocation density, and better expansion performance. Cu-bearing DH steel achieved an excellent match of strength and plasticity of 1289 MPa × 19.8%, with the hole expansion rate of 21.9% and the loss rate of hole expansion rate of 10%.

Innovative dodecane-hexadecane/expanded graphite composite phase change material for sub-zero cold storage applications

Utilization of phase change materials (PCMs) for cold energy storage has garnered increasing attention. This study focuses on the development of a composite PCM by integrating a novel eutectic dodecane-hexadecane (DD-HD) PCM into expanded graphite (EG), to cater to the demands of sub-zero cold energy storage applications, such as cold chain logistics. The study identified the optimal mass ratio of DD-HD as 80:20. A series of DD-HD/EG composites were fabricated through a combination of high-speed emulsification and physical adsorption methods. The adsorption capacity of EG for the eutectic PCM mixture was evaluated by examining the impact of EG fraction on the leakage of the composite PCM, revealing that the optimum EG fraction is 10 wt%. The composite PCM displayed a sub-zero phase change temperature of -12.09 ℃, a high melting enthalpy of 178.75 kJ/kg, and a high thermal conductivity of 5.18 W/(m•K). The thermal conductivity of the composite was enhanced by 22.52 times compared to the base PCM. Thermogravimetric analysis indicated that the decomposition temperature of DD-HD/EG was significantly higher than that of the base PCM. The composite demonstrated outstanding thermal reliability, as evidenced by thermal cycle tests. With its impressive thermal characteristics, this composite shows great potential for various cold energy storage applications.

Thermal conductivity test and model modification of SiO2 aerogel composites based on heat flow meter method

In the composition of thermal protection system, lightweight and efficient super thermal insulation materials-aerogel and its composites have been paid more and more attention and applied in recent years. The heat transfer of aerogel composites is more complicated due to the influence of micro-scale additives, fiber distribution and coupling heat transfer of various heat transfer modes, so it is urgent to calculate the effective thermal conductivity (ETC) accurately. According to the variation law of gas, solid, gas–solid coupling and radiation thermal conductivity with temperature and pressure, the thermal conductivity test is conducted based on the heat flow meter method, so as to the mathematical models of thermal conductivity are modified. The modified models take into account the influence of various micro-scale additives, which can accurately and quickly calculate the ETC of aerogel composites under different working conditions. The questions that different aerogel composites need to reconstruct structural models and the existing theoretical formulas are inaccurate in calculating ETC are solved. This paper is of great theoretical value to accurately predict the thermal insulation performance of aerogel composites.

Low Current Density Cathode Plasma Electrolytic Deposition of Aluminum Alloy Based on a Bipolar Pulse Power Supply

The present paper reported a novel bipolar-pulse cathodic plasma electrolytic deposition (BP-CPED) technique with a low current density. This newly developed CPED technique can break down the barriers of the existing CPED technique with higher current density. In this report, ceramic coatings were successfully prepared on aluminum alloy via the BP-CPED technique in an aqueous carbamide-based electrolyte. Data recording results in the reacting process show that there is the current density of the cathode below 0.15 A/cm2 and that of the anode below 0.035 A/cm2, which approximately reaches the level of conventional MAO technique. Interestingly, the addition of PEG into the electrolyte can further reduce the current density and effectively improve the coating quality. The kinetic of the BP-CPED process was discussed based on the evolution of current density/voltage-time curves and spark discharge phenomena. SEM observations illustrate that BP-CPED coatings possess a typical porous-surface feature. XRD analysis indicates that the coating was mainly composed of Al2O3 and Al4C3. Al2O3/Al4C3/ZrO2 composite coatings fabricated after Zr-doping reflected the successful Zr-incorporation into the coating, which demonstrated that the BP-CPED technique can be used to design the coating composition by the doping modification. The direct pull-off and thermal shock tests confirmed that new BP-CPED coatings obtained under the cathodic plasma discharge have excellent bonding strength. It is possible that this novel BP-CPED technique can provide a promising choice in developing the large-area CPED surface treatment for the industrial application.

Investigation on the Thermal and Wettability Properties Aided with Mechanical Test Simulation of Tin (Sn) - Bismuth (Bi) Solder Alloy at Low Reflow Temperatures

The current study proposes to investigate the thermal, wettability and mechanical properties of a low temperature SnBi solder. The main aim is to investigate the performance of the SnBi solder alloy with different Bi composition. The study also establishes the relationship between melting temperature, spreading area and tensile stress of the SnBi with different Bi composition at different low reflow temperatures. The thermal and wettability tests are conducted experimentally, while the mechanical test will be analysed via finite element analyses (FEA). The single shear lap test method was adopted for the simulation. The thermal properties of the SnBi solder are investigated using the differential scanning calorimeter (DSC). The reflow temperature selected ranges from 160 °C to 220 °C to accommodate the purpose of low temperature soldering. Wetting test results showed that spreading area of Sn48Bi solder alloy increased to 28.1 and 42.88 at 180 °C and 210 °C respectively. The increase in the Bi composition reduced the tensile strength regardless of the increase of the reflow temperature. The preliminary results commend the characteristics of the SnBi solder as a possible alternative to the Pb solder.

Monitoring of compressive strength gain in mass concrete using embedded piezoelectric transducers

AbstractThis study extended the electromechanical impedance (EMI) technique to monitor the 28‐day age of strength gain in mass concrete, although it has been validated in strength monitoring of a lab‐scaled concrete specimen. Embedded piezoelectric (PZT) transducer, namely, aluminum embedded PZT (AEP), that was wrapped by two sandwich aluminum pastes was proposed for EMI monitoring. The workability of the AEP was first verified via finite element analysis, where the effect of hydration heat on the EMI signature of the AEP was evaluated via numerical modeling and prior thermal test. In the experiment, totally four AEP transducers arranged at different loci were applied to monitor strength gain in a mass concrete specimen. As a comparison, the maturity method was also performed to estimate the strength of the specimen. Characteristics of EMI signature and its statistical indices including root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD) were analyzed and correlated to strength development in mass concrete. Monitoring results indicated that the AEP transducers were capable of identifying the strength gain of mass concrete. The logarithmic function between the RMSD/MAPD index values and compressive strength perfectly predicted the strength development, which could be further employed for real‐life and in situ applications.

Design of a power processing unit with integrated telemetry for a vacuum arc thruster as part of the SeRANIS mission

In this work the design and development of a power processing unit for a vacuum arc thruster is presented. The thruster is part of the Seamless Radio Access Networks for Internet of Space (SeRANIS) mission of the University of the Bundeswehr Munich, which will work as first multifunctional laboratory in orbit with public access. In addition to the basic functionality of generating a voltage peak for igniting the thruster, the power processing unit is equipped with techniques for controlling the ignition sequence and monitoring desired key values. The ignition procedure starts with generating the first trigger signal up to the point where a full-blown plasma is established. The PPU guarantees reliable performance by blocking every additional incoming signal while the ignition sequence is under way and the separation of the satellite’s power bus before the thruster discharges. The status of the power processing unit is constantly controlled and information is provided whether ignition was successful or not. The functionality of this circuit is based on simulation before assembly and testing. In addition, the presented system was designed to pass a test cycle of mechanical, thermal and electrical tests before being declared ready for the space mission.

Research on the Preparation and Performance of Biomimetic Warm-Mix Regeneration for Asphalt Mixtures

To determine the formula for biomimetic warm-mix regeneration and fulfill the requirements of a “high waste asphalt mixture content, high quality, and high level” for its usage in reclaimed asphalt pavement (RAP), this paper first determined the suitable preparation process and formula for biomimetic warm-mix regeneration based on orthogonal experiments and a gray correlation analysis. Then, the optimum dosage of the warm-mix regenerant was determined by a uniaxial penetration test, low-temperature splitting test, and freeze–thaw penetration test. The rutting test was conducted to characterize the high-temperature performance of the asphalt mixture. The Immersion Marshall Test and the freeze–thaw splitting test were used to characterize the water stability of the recycled asphalt mixture. The low-temperature small beam test was employed to study the low-temperature performance of the recycled asphalt mixture. The asphalt’s short-term and long-term aging processes were simulated using the rotary thin-film oven test (RTFOT) and the pressure aging test (PAV). The action mechanism of biomimetic warm-mix regeneration was revealed by Fourier-transform infrared spectroscopy (FTIR). Finally, a comprehensive thermal performance test was conducted on the aged asphalt after biomimetic warm-mix regeneration. The results showed that the self-made biomimetic warm-mix regeneration agent exhibited an excellent regenerative effect on RAP and significantly reduced the mixing temperature of the styrene–butadiene–styrene (SBS)-modified asphalt mixture. In addition, the self-made biomimetic warm-mix regeneration agent effectively improved the high- and low-temperature performance of the recycled asphalt mixture, but had no noticeable effect on the water stability. The suggested dosage of the biomimetic warm-mix regeneration agent was 6%, and the mixing temperature was 130 °C. The microscopic chemical analysis revealed that biomimetic warm-mix regeneration restored the performance of aged asphalt by supplementing the light component. The change rules of the chemical functional groups and the comprehensive thermal properties of the recycled mixture showed a good correlation with the change rules of its high- and low-temperature performance.

Thermal response tests on boreholes in multi-layered ground with geothermal gradient

The design of ground source heat pump systems requires knowledge of the properties of the ground and boreholes, which are often measured through thermal response tests (TRTs). Conventional TRT analysis methods apply for uniform ground properties and undisturbed ground temperature. These assumptions become less valid for deeper boreholes, which penetrate more ground layers while the geothermal gradient becomes more important. In multi-layered ground without a geothermal gradient, conventional methods estimate the effective ground thermal conductivity kgr near the thickness-weighted average, but a geothermal gradient adds complications. In the present study simulated TRTs with quasi-steady-state and fully transient models demonstrate that the required test duration for conventional methods may become impractically large as the borehole depth increases. In general, this occurs when the dimensionless parameter |qratio| approaches 1 or less. This parameter represents the ratio of the externally imposed heat injection/extraction rate to the natural heat rate associated with the geothermal gradient. In these cases, the conventional methods do not estimate the thickness-weighted average value of kgr. On the other hand, a fully transient multi-layered ground model can determine the thickness-weighted average value of kgr. This model requires measured fluid vertical temperature profiles to estimate individual layer values of kgr within reasonable uncertainties.

[Cs14Cl][Tm71Se110]: An unusual salt-inclusion chalcogenide containing different valent Tm centers and ultralow thermal conductivity

As an emerging class of inorganic hybrid materials, salt-inclusion chalcogenides (SICs) have garnered significant attention in the past decade owing to their distinct host-guest structural characteristics and outstanding performance in the field of optoelectronics. In this study, a novel quaternary SIC [Cs14Cl][Tm71Se110] has been discovered using an appropriate flux method. The structure comprises two distinct parts within the lattice: the host [Tm71Se110]13− framework and the guest [Cs14Cl]13+ polycation. Notably, this structure reveals the presence of mixed-valent Tm2+/Tm3+ and different types of closed cavities for the first time. Additionally, thermal transport performance testing shows that it has ultralow thermal conductivity, ranging from 0.29 to 0.24 W/m⋅K within the temperature range of 323–673 K, which is one of the lowest reported values among polycrystalline chalcogenides. This research not only advances the coordination chemistry of rare-earth-based compounds but also reaffirms that SIC semiconductors are promising systems for achieving ultralow thermal conductivity.

Roles of lattice and grain boundary on hydrogen diffusion and trap behaviors in single-and poly-crystalline CrCoNi medium-entropy alloy

In this study, single-crystalline and poly-crystalline CrCoNi alloys are utilized as model systems to analyze the distinct roles of each GB and interstitial lattice sites. To effectively reveal hydrogen behavior, both electrochemical and gaseous hydrogen pre-charging methods are applied. Hydrogen content, diffusivity, and trap behaviors are quantified using thermal desorption analysis and hydrogen permeation tests, which determines (1) changes in hydrogen behavior depending on the presence of GB and (2) alterations in hydrogen behavior depending on lattice crystallographic orientation. The results indicate that GB and interstitial lattice sites exhibit comparable binding energies for hydrogen trapping. However, the introduction of GB alters the primary trapping sites from interstitial lattice sites to GB. In this case, the hydrogen content in the poly-crystalline alloy is determined by the trap site density of the primary trapping site. On the other hand, in the single-crystalline alloy, where only interstitial lattice sites exist, the crystallographic orientation of the hydrogen-charged plane is an important variable that determines hydrogen content and hydrogen diffusivity. Such insights contribute to a deeper understanding of hydrogen behavior within a more intricate microstructure, suggesting the alloy design approach to enhance resistance to HE.

Thermal spray to embed optical fibers for the monitoring and protection of metallic structures

In the framework of using fiber optics (FO) for structural health monitoring, a true challenge is to fix the fiber onto structures guaranteeing both protection for the former and an effective adhesion on the latter. This work proposes a method to obtain such result via thermal spray technique on metallic structures, allowing its use in the most severe conditions of corrosion and wear. Since the transmission medium between the structure and the sensitive part of the optical fiber is represented by the fiber coating, three differently coated fibers were used on C-40 steel substrate: polyacrylate, polyimide and ORMOCER. In addition, the use of a primer to improve the bond on the substrate was evaluated. The adhesion between FO and metallic coating is evaluated through optical microscopy (OM) and scanning electrons microscopy (SEM) analysis. The functionality is also verified with both thermal and mechanical tests to calibrate the measuring accuracy. The results indicate that the best combination is that of the polyimide fiber, a zinc primer and aluminum coating. The proven qualities are the adhesion at the interface between the metallic coating and the fiber optics, and the preservation of the structural integrity of the fiber itself and its coating, and a precise measurement of strain acquired by fiber Bragg grating sensors (FBGs). The use of the thermal spray process is thus proved to be a solution for the optical fiber and substrate interaction, since it preserves the integrity of the optical fiber, due to the low temperature of the process, adding the protection that the metallic coating offers as well.

Optimization of flow behavior models by genetic algorithm: A case study of aluminum alloy

Prediction of the flow stress of materials using a flow constitutive model provides strong support for engineering practice and promotes the continuous development of aluminum alloys and relevant application fields. Optimizing the parameters of flow constitutive models is a key concern to explain and predict the flow behavior. In this study, a genetic algorithm (GA) is used to optimize the parameters of flow constitutive models widely used for the flow behavior of Al alloy including modified Johnson-Cook model, hyperbolic sinusoidal Arrhenius-type model, SK-Paul model, modified Zerilli-Armstrong model, Kobayashi-Dodd model, and modified Fields-Backofen model. AA6061−T6 alloy is used in this study since it has been used as a representative Al alloy. The performance of the models optimized by GA was evaluated through comparative analysis with mechanical test. The Gleeble-3800 thermal simulation testing apparatus was employed to conduct unidirectional thermal compression tests under multi conditions, including different temperatures (573 ∼ 783 K), diverse strain rates vary from 0.001 to 1 s−1, and a range of strains (0 ∼ 0.8). The performance of all the models optimized by GA is enhanced, and the optimization effect of GA on SK-Paul model is most pronounced, which exhibits a maximum correlation coefficient (R) of 0.99731 and a minimum average absolute relative error (AARE) of 6.53%. The findings highlight the validity of GA optimization in flow constitutive models in the prediction of the flow behavior of Al alloy.

Birefringent optical fibers to decouple thermo-mechanical effects on FBG sensors

Optical fiber Bragg (FBG) sensors are gaining importance in structural health monitoring (SHM) systems due to their compact size and ability to be embedded into the lamination sequences of composite material elements. A significant challenge, widely discussed in the literature, concerns the decoupling of thermomechanical measurements made through these sensors. This work aims to solve this problem using birefringent optical fibers instead of conventional ones. The distinctive characteristics of birefringent fibers allow an FBG sensor, written in such fibers, to present not a single peak but two distinct peaks, each with different responses to changes in strain and temperature. This is due to the different refractive index distribution in the fiber core section, which allows for two axes on which the light signal propagates at different speeds. This property offers a significant advantage: by having two independent equations associated with the two peaks, it is possible to decouple the thermomechanical measurements using only the fiber itself, without the need to introduce additional components to achieve mechanical decoupling (capillaries with through or interrupted fiber). This would ensure that strain and temperature are measured at the same point. In the first phase of the work, an FBG sensor on a birefringent fiber was characterized and subsequently calibrated. Therefore, a dedicated experimental set-up was created to conduct thermal, mechanical, and thermomechanical characterization tests, in order to verify the feasibility and effectiveness of decoupling. In a second step, such sensor was embedded within a sample of composite material (unidirectional glass fibers), which was subsequently subjected to the same characterization tests conducted on the single fiber. The results highlight the ability of this new transducer to decouple the thermal effect from the mechanical effect, allowing this new technology to overcome the problems of FBG sensors made of standard fibers.

Water absorption and property evolution of epoxy resin under hygrothermal environment

Changes in structure and properties of resin matrix caused by water absorption is one of the key factors affecting the long-term durability of fiber reinforced polymer composites used in civil engineering. In the present study, the water diffusion and structural change in an epoxy resin were investigated experimentally through immersion in deionized water at 40, 60 and 80 °C for 135 days. Water absorption, thermal, mechanical and microstructure analysis tests were conducted to evaluate the long-term property evolution. It was found that the water absorption of epoxy resin followed a two-stage model, including an initial Fick's diffusion response and a subsequent relaxation response. Long-term hygrothermal exposure brought about the structural change of epoxy resin, which led to the significant degradation up to 8%–30% in the mechanical properties and 21% in glass transition temperature, respectively. The resin plasticization and hydrolysis was the key factors for the degradation of thermal and mechanical properties. It was proved that the plasticization effect was reversible with the remove of bonding water after the drying. Based on the Arrhenius equation, the long-term life of flexural strength in two service environments were predicted to provide the application guideline. The significant degradation of flexural strength was occurred at the initial exposure of 2000 days and then reached to the stable strength retention of 69.6%.