External Temperature Changes Research Articles

A data-driven probabilistic harmonic power flow approach in power distribution systems with PV generations

Large-scale electrification in the end-user and renewable energy fields is one of the key pathways to achieving carbon neutrality by 2050. Meanwhile, a large number of power electronic devices are used in residential, commercial, and office loads and photovoltaic (PV), which leads to the power quality harmonics in the power distribution system (PDS) becoming more prominent than ever before. Due to the nature of the random behavior of users and random changes in external factors, e.g., illumination and temperature, the harmonics in the PDS are strongly random and time-varying, which makes it hard to evaluate and mitigate the harmonics using the individual deterministic harmonic power flow (HPF) approach. This paper proposes a data-driven piecewise probabilistic HPF method for the PDS with PVs. First, a data-driven piecewise probabilistic harmonic cross coupling model is proposed for analyzing the harmonics generated by different harmonic sources, and the probabilistic and time-varying features can be manifested via this model. Moreover, this proposed harmonic model has a certain predictive capability. Then, the decoupled method based on graph theory and injection current is developed for computing the HPF. Finally, a field theory-based piecewise probabilistic HPF is applied for assessing the probabilistic harmonics of the PDS with PVs. Actual measurements for various harmonic sources and simulations in three different sizes of IEEE systems validate the precision, effectiveness, and efficiency of the proposed models and methods.

Establishment and experimental verification of temperature prediction model for quick‐frozen strawberry jetted with dry ice

AbstractIn this study, the quick‐freezing model and heat transfer model of quick‐freezing of strawberries with dry ice at different flow speeds were proposed to ensure the quality of quick‐frozen strawberries and control the jetting amount of dry ice. The aim of this study was to investigate the changes of internal and external temperature in the process of quick‐freezing strawberries by jetting dry ice. The quick‐freezing experiment platform of strawberries based on dry ice jetting was built for a quick‐freezing experiment of strawberries at a dry ice jetting flow speed of 0.30 m/s. As indicated by the results, the temperature of strawberries was more uniform under the dry ice jetting speed of 0.30 m/s. The highest and lowest temperature differences between the surface and center of strawberries (the simulated) were 15.7 and 39.7°C, respectively, and the quick‐freezing time of strawberries was 345 s. Compared with the experimental result, the error of quick‐freezing completion time was 5.79%. The differences measured in the experiment were 15.1 and 37.7°C, and the error accounted for 4.73% and 7.89%, respectively. The accuracy of the model was measured, mean relative error = 6.31% and root mean square error = 10.78%. As revealed by the results, the model had high universality and precision and could be used to analyze the temperature change during dry ice jetting‐based quick‐freezing of strawberries. The quality indexes of quick‐frozen strawberries before and after dry ice jetting were found to be better than the standard of quick‐frozen strawberries. Thus, the research results can provide a reference for a further development of energy‐saving and environmental dry ice jetting‐based quick‐freezing equipment.

The effect of environmental variables and metabolic rate on physiological parameters in a hot and humid mine

The problem of high temperature has always been a challenge for safe mining in deep mines. At present, breakthroughs in key technologies have not been achieved. The effects of environmental variables and metabolic rate on physiological parameters has important guiding significance for ensuring the safety of miners. In this study, the changes in the physiological parameters of the human body were determined through experiments to simulate the underground environment. The results show that ambient temperature, metabolic rate and working time are all positively correlated with heart rate, blood pressure and external auditory canal temperature. Heart rate and blood pressure show a rapid increase first and then a slow increase. Regardless of the influence of humidity on heart rate and blood pressure, the relationship formulas between dependent variable (HR, SBP, and DBP) and independent variable (metabolic rate and working time) is obtained. These findings show that labor intensity and working time are the direct factors leading to changes in heart rate, blood pressure, and external auditory canal temperature, while ambient temperature is the indirect cause, and the influence of wind speed is minimal. The experimental results show the importance of factors affecting human physiological parameters.

Toward Confocal Chromatic Sensing in Nuclear Reactors: In Situ Optical Refractive Index Measurements of Bulk Glass

To measure fuel rod swelling in a nuclear research reactor, our research has focused on the development of an optical confocal chromatic sensor, allowing contactless measurements of radial changes in fuel rods. This sensor must be able to operate in the harsh and hot environment of a reactor, especially under high neutron fluences up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{19}~{n}_{\mathrm{ fast}}/\text {cm}^{2}$ </tex-math></inline-formula> and gamma doses of a few GGy. When exposed to such radiation levels, the properties of bulk optical glasses are known to be affected by two main phenomena: radiation-induced attenuation (RIA) and radiation-induced refractive index change (RIRIC). With the objective of testing glasses as candidates for a future confocal chromatic sensor, we created a dedicated setup for the online monitoring of the glasses’ RIRIC in the core reactor with a measurement principle relying on interferometry. Since not only the refractive index (RI) but also the length of the samples changes under neutron radiation through compaction, we measured the variation of the optical path (OP) ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$nL$ </tex-math></inline-formula> ). To assess the performance of our setup, preliminary in-lab tests were performed to evaluate the feasibility of measuring the small RI changes caused by external temperature changes. Due to this study, we were able to obtain data that were not yet available in the literature regarding the temperature-induced RI variation of several bulk glasses, including radiation-hardened glasses, up to 350 °C. This information is crucial for the targeted application, as the confocal chromatic sensor will have to operate at such elevated temperatures.

Establishment and optimization of temperature compensation model for benzoic acid detection based on terahertz metamaterial

To regulate the use of food additives is of great significance to human health, for the excessive use of food additives can cause damage to human body so serious as organ failure and even cancers. Benzoic acid (BA) is a widely used food preservative, and it is of great importance to achieve high-sensitive detection of it. Conventional THz detection method can obtain the fingerprint spectrum of the sample in the terahertz band, it can only detect a sample to be detected at a milligram level, and it is not suitable for the micro or trace analysis of the sample. In this paper, an enhanced terahertz (THz) micro-nano structure of metamaterial based on electromagnetic theory was designed to achieve enhanced detection of benzoic acid additives by THz technology. THz spectroscopy is more sensitive to temperature changes than other spectroscopic detection techniques, so it is particularly important to find out a method of spectral temperature compensation to minimize the inference caused by temperature variations in the detection of samples with variable temperature. To this end, based on the enhanced technology of THz metamaterial, an optimized compensation method for external temperature variations was explored in this paper. Firstly, the THz spectra of seven samples with different concentrations under six different temperatures were collected. Secondly, smoothing and baseline correction methods were used to preprocess the spectra to study the better spectral pretreatment methods. To reduce the influence of the change of external temperature on the detection, the External Parameter Orthogonalization (EPO) and Generalized Least Squares Weighting (GLSW) methods were introduced to compensate the temperature change. These two aforementioned methods were compared with the method without temperature compensation, respectively. Then, Uninformative Variable Elimination (UVE), principal component analysis (PCA),successive projections algorithm (SPA) and Competitive Adaptive Reweighted Sampling (CARS) were used to explore the optimal terahertz band selection method. Finally, Partial Least Squares (PLS) and Least square support vector machine (LS-SVM) models were established, respectively, to realize the enhanced detection of benzoic acid additives. The LS-SVM model combined with SPA and GLSW has the best effect, with the Rp2 of 0.9892, the RMSEP of 3.8412 × 10−5 and the LOD of 1.158 × 10−4 g/mL. The LOD of the model is nearly three times higher than that of the mixed global model. The results show that the GLSW method exhibited a better compensation effect on the THz spectra of benzoic acid solution samples at different temperatures. Therefore, this study can be applied to other temperature-compensated models and can also provide reference for the detection of samples with variable temperature.

Preparation of mechanically robust and thermochromic phase change materials for thermal energy storage and temperature indicator

Phase change materials (PCMs) capable of thermal energy storage (TES) have been drawn great attention as an important strategy to deal with energy shortage. Herein, a novel thermochromic solid–solid PCMs (SSPCMs) based on polyethylene glycol has been successfully synthesized, which possess mechanically robust properties and intriguingly thermochromic function besides TES. These devised thermochromic SSPCMs hold high melting latent heats with a maximum value at 113.4 J g−1. Additionally, the highest ultimate tensile strength of prepared SSPCMs featuring with excellent stretchability (658.3%) can reach 14.8Mpa, endowing them with the practical application for more scenarios. Particularly, these thermochromic SSPCMs can change itself color from purple to pink during the phase transition process, which can be acted as a temperature indicator. Surprisingly, the color of the thermochromic SSPCMs can change in just 3 s under 90 ℃, rapidly responding the change of external temperature. For this, these thermochromic SSPCMs can be coated on delivery pipeline, which not only plays thermal insulation function, but also makes the corresponding color change by sensing the change of liquid temperature in the pipeline for playing a warning role. Combination of color change function and thermal energy storage in the devised SSPCMs not only realizes the storage and release of latent heat, but also provides real-time indication of the saturation-depletion state of energy. This design route provides an attractive way to solve the dilemma of traditional PCMs with a single TES function and broaden its applied fields.

Er-Based Luminescent Nanothermometer to Explore the Real-Time Temperature of Cells under External Stimuli.

Temperature as a typical parameter, which influences the status of living creatures, is essential to life activities and indicates the initial cellular activities. In recent years, the rapid development of nanotechnology provides a new tool for studying temperature variation at the micro- or nano-scales. In this study, an important phenomenon is observed at the cell level using luminescent probes to explore intracellular temperature changes, based on Yb-Er doping nanoparticles with special upconversion readout mode and intensity ratio signals (I525 and I545 ). Further optimization of this four-layer core-shell ratio nanothermometer endows it with remarkable characteristics: super photostability, sensitivity, and protection owing to the shell. Thus this kind of thermal probe has the property of anti-interference to the complex chemical environment, responding exclusively to temperature, when it is used in liquid and cells to reflect external temperature changes at the nanoscale. The intracellular temperature of living RAW and CAOV3 cells are observed to have a resistance mechanism to external stimuli and approach a more favorable temperature, especially for CAOV3 cells with good heat resistance, with the intracellular temperature 4.8 °C higher than incubated medium under 5 °C environment, and 4.4 °C lower than the medium under 60 °C environment.

Cost-efficient and reliable annular optical fiber temperature sensor.

In this paper, an annular winding structure made of single-mode optical fiber is proposed as the core of a cost-efficient and reliable annular optical fiber temperature sensor (AOFTS). The sensor is mainly due to the multi-mode interference effect to achieve real-time response to external temperature changes. The experimental results show that the average temperature sensitivity of the sensor is about 255.5 pm/°C in the temperature range of -20∘C-110∘C; it has higher sensitivity at low temperatures. At -20∘C, the sensitivity of the AOFTS reaches 450 pm/°C. The sensor has the advantages of simple fabrication, low fabrication cost, strong stability, and good reproducibility and repeatability. It has great application prospects in the field of low-temperature detection.

An Optical Sensor Designed From Cascaded Anti-Resonant Reflection Waveguide and Fiber Ring-Shaped Structure for Simultaneous Measurement of Refractive Index and Temperature

A novel optical fiber sensor based on cascade anti-resonant reflection waveguide (ARRW) and fiber ring-shaped structure (FRSS) is proposed and experimentally demonstrated for simultaneous measurement of refractive index (RI) and temperature. The sensor is very simply fabricated by splicing ARRW and FRSS based on Mach-Zehnder interference (MZI). The FRSS interference dip is sensitive to external RI and temperature changes, whereas the ARRW structure's loss dip is only sensitive to external temperature. As a result, this sensor can be used to measure both RI and temperature simultaneously. The sensor's maximum RI sensitivity is 108.61 nm/RIU and its maximum temperature sensitivity is 19 pm/ °C in the experiment. This sensor is a good choice when it is necessary to measure RI and temperature at the same time due to its compact size, high sensitivity, low cost, and good stability.

Switchable frequency terahertz vortex beam generator

Most of the reported vortex beam generators generate vortex beams at a fixed frequency, which limits the practical applications. Therefore, it is inevitable to explore a vortex beam generator, which can actively control the operating frequency. We propose a switchable frequency terahertz vortex beam metasurface, it is freely switchable under single-frequency mode and dual-frequency mode by changing the external temperature, the phase state of vanadium dioxide (VO&lt;sub&gt;2&lt;/sub&gt;) is also changeable. External temperature changes will cause VO&lt;sub&gt;2&lt;/sub&gt; to transform from insulating state to metallic state. Generally, VO&lt;sub&gt;2&lt;/sub&gt; conductivity can increase by several orders of magnitude as operating temperature changes. By using the phase change property of VO&lt;sub&gt;2&lt;/sub&gt;, we can obtain a metasurface with switchable operating frequencies. For operating at room temperature, the proposed metasurface behaves as a single-frequency terahertz vortex generator. When (left-handed circularly polarized, LCP) terahertz wave is vertically incident on the metasurface, it generates vortex beams with different topological charge numbers at a frequency of 1.1 THz, and the mode purity is above 85%. The simulation results show that the mode purity of the vortex beam with the topological charge &lt;i&gt;l&lt;/i&gt; = 1 is 90%, and the mode purity is about 91.1% for the vortex beam with &lt;i&gt;l&lt;/i&gt; = 2, and 85.4% for the vortex beam with &lt;i&gt;l&lt;/i&gt; = 3. When the external temperature is of 68 ℃, the designed metasurface becomes a dual-frequency vortex beam generator. At this time, the operating frequencies of vortex beams with different topological charges (&lt;i&gt;l&lt;/i&gt; = 1, 2, 3) are 0.7 and 1.23 THz, whose mode purities are both above 60%. That is to say, the corresponding mode purities at topological charge with&lt;i&gt; l&lt;/i&gt; = 1 for two operating frequencies are 89.1% and 71.6%, respectively. The mode purities are 83.2% and 94.4% with topological charge &lt;i&gt;l&lt;/i&gt; = 2, respectively. The mode purities are 62.4% and 68.2% with topological charge&lt;i&gt; l&lt;/i&gt; = 3, respectively. Therefore, the proposed switchable frequency terahertz vortex generator provides a new design idea for working frequency modulation in wireless terahertz communication.

Design of an information-measuring system for monitoring deformation and displacement of rock massif layers based on fiber-optic sensors

This paper reports a study into designing an information-measuring system that could be used in coal mines that are dangerous in terms of the explosion of coal dust and methane gas. The results of reviewing technical advancements in the field of fiber-optic system development are given. To solve the set task, prototypes of a fiber-optic sensor of a new type and a hardware-software complex were constructed. The research aims to improve the safety of workers at coal enterprises. The result of the theoretical research has established that additional losses related to a micro bending should be taken into consideration while accounting for the effect of photoelasticity. The fundamental difference between the idea reported here and existing analogs is the development of a hardware-software complex capable of working with a single-mode optical fiber of great length with a significant noise level. The data processing unit is equipped with a television matrix and can analyze changes in the pixels of a light spot. The proposed system is quasi-distributed; it controls individual points within a rock massif. The designed hardware-software system provides high noise immunity of measuring channels when the external temperature changes. The research results helped develop an information-measuring system for monitoring the deformation and displacement of rock massif layers based on fiber-optic sensors, capable of operating in an explosive environment. The system makes it possible to control several layers located in the roof of the workings, while the fiber-optic sensor may contain two or three sensitive elements that are connected to different channels. With a sharp fluctuation in pressure and an increase in the displacement parameter, the system triggers a warning signal about the danger.

Fiber-optic temperature sensor based on beat frequency and neural network algorithm

A multi-longitudinal mode fiber laser sensor (MLMFLS) system based on neural network (NN) algorithm is proposed. Gaussian process regression (GPR) is used to denoise the beat frequency signal (BFS). The frequency change of BFS has a linear relationship with the applied external temperature change. Neural network algorithm is used to fit the linear relationship between the frequency of BFS and external temperature change. Processing and analysis of experimental data showed that the method fitted very well with the relationship between the beat frequency signal and external temperature change. The MATLAB App Designer tool is used to display the wide band frequency spectrum, frequency of BFS and corresponding temperature change. The sensitivity of single beat frequency is 5.204 kHz/℃, the maximum absolute error is ± 0.15 ℃ and the average error is 0.072 ℃. The five beat frequencies sensitivity is 5.206 kHz/℃, the maximum absolute error is ± 0.09 ℃ and the average error is 0.055 °C. Through the combination of neural network algorithm and beat frequency sensing system, simple, fast and real time temperature sensing is realized.

A Temperature Control Method for Microaccelerometer Chips Based on Genetic Algorithm and Fuzzy PID Control.

External temperature changes can detrimentally affect the properties of a microaccelerometer, especially for high-precision accelerometers. Temperature control is the fundamental method to reduce the thermal effect on microaccelerometer chips, although high-performance control has remained elusive using the conventional proportional-integral-derivative (PID) control method. This paper proposes a modified approach based on a genetic algorithm and fuzzy PID, which yields a profound improvement compared with the typical PID method. A sandwiched microaccelerometer chip with a measurement resistor and a heating resistor on the substrate serves as the hardware object, and the transfer function is identified by a self-built measurement system. The initial parameters of the modified PID are obtained through the genetic algorithm, whereas a fuzzy strategy is implemented to enable real-time adjustment. According to the simulation results, the proposed temperature control method has the advantages of a fast response, short settling time, small overshoot, small steady-state error, and strong robustness. It outperforms the normal PID method and previously reported counterparts. This design method as well as the approach can be of practical use and applied to chip-level package structures.

Investigation of magneto-electro-thermo-mechanical loads on nonlinear forced vibrations of composite cylindrical shells

In this article, in order to investigate the nonlinear forced vibrations in multi-physics fields, a coupled nonlinear modeling for composite cylindrical shells is developed by the improved Donnell nonlinear shell theory and Maxwell static electricity/magnetism equations. The nonlinear governing equations are obtained by Hamilton principle, and then the partial differential equations are transformed into sixty-degree-of-freedom nonlinear ordinary differential equations through multi-mode Galerkin technique. Afterwards, numerical simulations are conducted by the pseudo-arclength continuation algorithm. The comparisons and validations show that the present procedure is capable of solving coupled multi-modes nonlinear partial differential equations. Finally, the effects of the external temperature change, magnetic potential, electric potential, excitation amplitude on nonlinear vibration response of composite cylindrical shells are evaluated.

A High-Sensitivity Low-Temperature Sensor Based on Michelson Interferometer in Seven-Core Fiber

An in-fiber Michelson interferometer (MI) formed by seven-core fiber (SCF) for low-temperature sensing is proposed and experimentally demonstrated. The sensor head is constructed by a section of seven-core fiber splicing a single-mode fiber (SMF) with a taper. When the external temperature changes, the interference spectrum of the MI will shift due to thermal expansion and thermo-optic effects. By measuring the wavelength variations of the interference dip, the external temperature can be determined. Experimental results proves that the sensor exhibits a maximum linear temperature sensitivity of −0.0775 nm/°C in the temperature range of −60 °C to 15 °C, and the standard deviation is 5% in stability test. The sensor possesses high sensitivity and easy fabrication, which makes it could be a good candidate in low-temperature sensing application.

Thermal performance of energy-efficient buildings for sustainable development.

Thermal performance of civil structure has turned out to be a demanding application in civil engineering and architecture. Thermal comfort (heating, ventilation, air cooling, airtightness, fabric performance) in buildings keeps the occupants energetic and positive. The study's objective is to maintain residents' comfort levels in their homes in the elimination of heat and humidity. Therefore, findings indicate that it is necessary to design a structure according to thermal comfort, decrease in carbon emission, air flows, electricity control, fuel, etc. This article provides detailed information about civil engineering structures' excellent and bad thermal performance, including buildings like residential, commercial, and educational institutions. This article provides an incisive assessment of the thermal performance, thermal comfort, thermal resistance, and thermal sensation of residential, commercial, and educational structures. The article contains in-depth information as well as case studies on how to improve indoor air quality and energy efficiency. Additionally, the topic of building energy consumption is discussed. The use of thermal performance of various building in various climatic circumstances has been discussed extensively in the works provided. A building's thermal performance determines how quickly heat enters the building and how quickly it is warmed. Heat travels faster through a poorly performing building, and the interior temperature is ultimately dependent on external temperature and climate changes. The thermal performance of different types of buildings such as residential, commercial, and educational buildings was analyzed in this study.

Recent advances of overcharge investigation of lithium-ion batteries

Lithium-ion batteries have been widely used in the power-driven system and energy storage system, while overcharge safety for high-capacity and high-power lithium-ion batteries has been constantly concerned all over the world due to the thermal runaway problems by overcharge occurred in recent years. Therefore, it is very important to study the thermal runaway mechanism and improve the safety of the battery during overcharge. In this work, depending on the external appearance, voltage, and temperature changes, the whole overcharge to TR process was divided into 5 stages. By analyzing the side reactions in five stages, the mechanism of heat production during overcharge is summarized, and the order of heat generation is QCa+An > Qanode > Qelectrolyte > Qcathode > QSEI > QISC. Key factors for battery overcharge safety, such as cathode materials, electrolyte safety, and charging current are concluded in this review. Compared to external protection devices (such as BMS, OSD, CID), the internal protection of overcharge additives are more effective. A complex polymer with aromatic functional groups, epoxy or propionate, will become a hot spot in the research of overcharge additives for lithium-ion batteries. This review is expected to offer effective overcharge safety strategies and promote the development of lithium-ion battery with high-energy density.

Study on the protective effect of the dense slag layer on converter lining

AbstractIn this paper, the protective effect of the dense slag layer on the furnace lining is investigated through comparative sampling of residual bricks. The physical and chemical properties of the residual brick samples were tested, and the result showed that sample NO.1 had 7.9% higher bulk density, 37.6% lower apparent porosity, 41% higher flexural strength, and 14.3% higher compressive strength than sample NO.2. The residual carbon of sample NO.1 was normal, while the residual carbon oxidation loss rate of sample NO.2 was 36%. X‐ray diffractomer (XRD), optical microscope (OM), and EDS: scanning electron microscope‐Energy Dispersive Spectrometer (SEM+EDS) were adopted to study the physical phase composition, microscopic morphology, and mineral phase composition and distribution of the dense slag layer. The slag layer was found to be highly alkaline and oxidizing, with 58–73% RO phase, 17–26% phosphorus‐rich phase, and 6–16% base phase in the mineral phases. The FactSage 8.1 thermodynamic software was used to simulate and calculate the melting temperature of each mineral phase. The presence of the high melting point phase and RO phase in the dense slag layer is an important reason for its ability against high temperature and high oxidation. The formation of the dense slag layer was related to the saturated solubility of MgO. The results indicated that the extremely unstable saturated solubility of magnesia had a greater effect on the dissolution rate of magnesia particles. External temperature and oxidation changes are important factors affecting the saturated solubility of MgO in the slag layer, and reducing the internal‐external heat and mass transfer rate could effectively improve the service life of the furnace lining.

Development of smart window using an hydroxypropyl cellulose-acrylamide hydrogel and evaluation of weathering resistance and heat shielding effect

Reducing the amount of electricity used by cooling systems is essential for lowering CO 2 emissions; therefore suppressing increases in room temperature in an environmentally friendly manner requires the development of heat-shielding materials that autonomously control sunlight without the use of electricity. Hydroxypropyl cellulose (HPC) has attracted attention as a lower critical solution temperature (LCST) type of temperature-responsive polymer. HPC is a thermochromic material that changes its optical properties in response to changes in external temperature. In this study, acrylamide (AAm) and HPC with various molecular weights were used to prepare HPC-AAm hydrogels, and their optical, heat-shielding, and weathering-resistant properties were evaluated. UV–vis–NIR spectroscopy revealed that the solar transmittance ( αT sol ) of the HPC-AAm hydrogel decreased while its solar reflectance ( αR sol ) increased with increasing HPC concentration above LCST. The αT sol of low-molecular-weight HPC was found to be lower than that of high-molecular-weight HPC. In addition, the temperature inside a box constructed using an HPC-AAm hydrogel window was approximately 10 °C lower than that constructed using glass alone. Furthermore, the optical properties of the HPC-AAm hydrogel were found to hardly deteriorated even when continuously exposed to heat and UV radiation for 150 h. Therefore, the HPC-AAm hydrogel prepared in this study is expected to be useful as a heat-shielding material. • Hydrogels based on hydroxypropyl cellulose (HPC) acrylamide (AAm) were prepared. • HPC-AAm hydrogels show high αT sol values below the LCST. • αT sol decreases and αR sol increases with increasing HPC loading above the LCST. • The L-HPC-AAm hydrogel led to lower temperatures inside a simulated room. • The HPC-AAm hydrogel is stable when continuously heated and UV irradiated.

Multifunctional design of triangular lattice metamaterials with customizable thermal expansion and tunable bandgap properties

New approaches for realizing multifunctional research and tunable properties of materials are proposed by designing lattice metamaterials. In this study, the finite element method is used to study the bandgaps of the joint-bonded triangular cell lattice metamaterial. A new multifunctional design method is proposed for designing metamaterials with tunable bandgaps and specific thermal expansion properties. In this method, the geometric deformation characteristics of thermal expansion of materials are studied, and a design method for maximum bandgaps’ tunability under the condition of a specific coefficient of thermal expansion is proposed to realize the tuning of bandgaps’ characteristics based on external temperature change. Numerical results show that the proposed method and metamaterials can demonstrate significant tunability of bandgaps. This finding provides a common method for designing bandgaps’ tunable acoustic metamaterial systems, which have broad application potential under variable temperature loading and can be extended to other topological structures.