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Young’s Modulus Measurement of Metal Wires Using FBG Sensor
摘要： A novel Young’s modulus measurement scheme based on fiber Bragg gratings (FBG) is proposed and demonstrated experimentally. In our method, a universal formula relating the Bragg wavelength shift to Young’s modulus is derived and metal wires are loaded strain by using the static stretching method. The Young’s modulus of copper wires, aluminum wires, nickel wires, and tungsten wires are separately measured. Experimental results show that the FBG sensor exhibits high measurement accuracy, and the measurement errors relative to the nominal value is less than 1.0%. The feasibility of the FBG test method is confirmed by comparing it with the traditional charge coupled device (CCD) imaging method. The proposed method could find the potential application in the material selection, especially in the field that the size of metal wires is very small and the strain gauges cannot be qualified.
关键词： Young’s modulus,static stretching method,metal wire,Fiber Bragg grating
更新于2025-11-28 14:23:57
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Molecular dynamics simulation study on the structure and properties of polyimide/silica hybrid materials
摘要： A type of polyimide/silica (PI/SiO2) copolymer model was established through the dehydration of tetraethyl orthosilicate molecules (TEOS) and bonding to a silane coupling agent. The content of SiO2 was controlled by adjusting the number of molecules which bound to the TEOS. Finally, the silica was formed into a hybrid model (hybrid PI/SiO2) with a small molecule embedded in the PI. The model was optimized by geometric and molecular dynamics and the changes in the model structure, Young’s modulus, shear modulus, and glass-transition temperature (Tg) were analyzed. The results showed that the density and cohesive energy density of the composites could be improved by doping SiO2 in PI. Young’s modulus and shear modulus of PI/SiO2 hybrid materials were higher than undoped PI. The tensile strength reached 568.15 MPa when the doping content was 9%. Therefore, the structure design and content control of SiO2 was an effective way to improve the performance of a PI/SiO2 composite. The variation of Tg and tensile strength of PI/SiO2 hybrid composites is consistent with that of PI/SiO2 composite synthesized in real experiment, which will be a convenient method for new material design and performance prediction. ? 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 136, 47335.
关键词： molecular dynamics,shear modulus,Young’s modulus,polyimide/silica,glass-transition temperature
更新于2025-09-23 15:23:52
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Theoretical studies on the mechanical and electronic properties of 2D and 3D structures of Beryllium-Oxide graphene and graphene nanobud
摘要： In the present study, ab initio-based density functional theory (DFT) calculations were used to determine the effects of certain phenomena that can occur in the synthesis of Beryllium-Oxide (BeO) few-layer sheets, such as various types of defects, attaching nanocages onto the surface of graphene and attaching layers to each side of it on the mechanical and electronic properties of BeO graphene sheets. We also used the density of states (DOS) calculations to obtain a better understanding of the electronic properties of the studied nanostructures. In the first step, we calculated Young’s modulus for the pristine BeO graphene sheet that was found to be equal to 1.110 TPa. Next, the effect of small and large defects on the mechanical properties of the BeO graphene-like structure was examined, and we found that extracting one Be atom resulted in a lower Young’s modulus compared to that obtained after extracting one oxygen atom (1.087 TPa versus 1.104 TPa), demonstrating that Be had a greater effect on the stability and mechanical strength of BeO graphene than did oxygen. The same trend was found when comparing three atom vacancies with two missing Be atoms to those with two missing oxygen atoms. Furthermore, the effect of circular and rectangular shape defects was investigated, and the obtained results demonstrated that the increase in the diameter of defects with both shapes significantly decreased Young’s modulus and band gap energy values. Additionally, due to the number of detached atoms in shape defects which are more than those of small defects, this type of defect had a more destructive effect on the structure’s stability so that it decreased the Young’s modulus more than small defects. Moreover, the mechanical properties of the BeO graphene nanobud structure were determined in terms of placing different numbers of Be12O12 nanocages onto the graphene surface, and a similar decreasing trend was observed for Young’s modulus. Finally, we considered the mechanical properties of the bi- and three-layer BeO graphene-like structures and found that increasing the number of layers reduced Young’s modulus slightly. For both of the latter phenomena of attaching nanocages and layers, the band gap energy decreased.
关键词： BeO Graphene,Multi-layer,DFT,Defect,Young’s Modulus,Graphene Nanobud
更新于2025-09-23 15:23:52
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In Situ Quantification of the Young’s Modulus of Nuclei In Multiple Cellular States Using A Modified Fiber Probe Sensor
摘要： In this work, a modified fiber probe sensor (MFP sensor) with a considerable length-diameter ratio tip was developed to quantitatively characterize the Young’s modulus of the cell nucleus in multiple cellular states. The MFP sensor has a needle tip with an extended length of 30 μm and a diameter of 150 nm. The length of the tip exceeds the diameter of most cells, so that it can penetrate the cell membrane with minimal damage and reach the nucleus. This allows the measurement of the Young’s modulus of intact cell nuclei under different cellular states without the phenomenon that the cantilever contacts the cell membrane. Moreover, the stiffness of the MFP sensor is reduced by a factor of 25 to better match that of the cell membrane and nucleus, which enables high-precision mechanical measurements. The MFP sensor was successfully used to quantify the Young’s modulus of the intact cell nuclei in the non-adherent, adherent and early apoptotic states. Experimental results validated the capability and versatility of the developed method.
关键词： In Situ,Modified Fiber Probe Sensor,Young’s Modulus,Cell Nucleus,Atomic Force Microscopy
更新于2025-09-23 15:22:29
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Thermodynamics and structural stability of tissues for bio-imaging analysis – The case of intracranial aneurysm rupture risk assessment
摘要： Based on thermodynamic principles, structure stability analysis like stress response and fracture formation is well established for inorganic but not for organic bio-materials. In this study, three equations were established to assess intracranial aneurysm (IA) rupture risk based on patient's IA and internal carotid artery (ICA) angiography images, by incorporating tissue thermodynamics. Our objectives are: (1) establish foundations to help understand the physics behind the observed morphological changes prior to IA rupture, and (2) provide first-principles equations to aide in rupture risk assessment. Subsequently, we validated the new equations using available experimental and numerical simulation results, and revealed new IA rupture physics. In particular, our models correlated well with most of the available experiment and computer fluid dynamics simulation data. Among the three common structure failure modes, the axial stress and the bending moment loading are the control mechanism. The rupture risk reaches its peak when (1) the aneurysm inclination angle (ω) is close to 63.4°, (2) IA diameter / ICA diameter ?1, and (3) IA length / IA diameter ≈1.6. This study provides strong physical foundations and sound understanding to aid in rupture risk assessment. It presents insights on detailed thermodynamics that govern the previously observed IA rupture behaviors, reported from both experiments and numerical simulations. By integrating angiography images with first-principles tissue thermodynamics, we (1) advance the IA research, which is currently dominated by experimental and imaging-data-statistic approaches, and (2) introduce Calphad research into a new exciting research field - bio-imaging analysis.
关键词： Young's Modulus,Entropy,Thin-walled cylinders,Bio-imaging,Intracranial aneurysm
更新于2025-09-23 15:22:29
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Single-Layer Ag <sub/>2</sub> S: A Two-Dimensional Bidirectional Auxetic Semiconductor
摘要： Two-dimensional auxetic materials have attracted considerable attention due to their potential applications in medicine, tougher composites, defense and so on. However, they are scare especially at low dimension, as auxetic materials are mainly realized in engineered materials and structures. Here using first-principles calculations, we identify a compelling two-dimensional auxetic material, single-layer Ag2S, which possesses large negative Poisson’s ratios in both in-plane and out-of-plane directions, but anisotropic ultra-low Young’s modulus. Such a coexistence of simultaneous negative Poisson’s ratios in two directions is extremely rare, which is mainly originated from its particular zigzag-shaped buckling structure. In addition, contrary to the previously known metal-shrouded single-layer M2X (M = metal, X = nonmetal), single-layer Ag2S is the first nonmetal-shrouded M2X. Electronic calculations show that it is an indirect-gap semiconductor with gap value of 2.83 eV, and it can be turned to be direct with strain. These intriguing properties make single-layer Ag2S a promising auxetic material in electronics and mechanics.
关键词： ultra-low Young’s modulus,two-dimensional,buckling structure,auxetic material
更新于2025-09-23 15:22:29
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Enhanced performance of porous silicone-based dielectric elastomeric composites by low filler content of Ag@SiO <sub/>2</sub> Core-Shell nanoparticles
摘要： In the present work, micropores and a low filler content of Ag@SiO2 nanoparticles (NPs) are synchronously introduced into polydimethylsiloxane (PDMS) film to obtain porous dielectric elastomeric composites. The morphology and dielectric and mechanical properties of the composites are investigated. The resulting composites possess high dielectric permittivity, low dielectric loss and low Young’s modulus, which is beneficial to the requirements of a dielectric elastomer actuator. This study provides an effective method to prepare high-performance PDMS-based dielectric porous dielectric elastomeric composites filled with low filler contents of Ag@SiO2 NPs.
关键词： core-shell particles,dielectric loss,Young’s modulus,dielectric permittivity,elastomer,Porous materials
更新于2025-09-23 15:22:29
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Young’s modulus and fatigue investigation of aluminum nitride films deposited on 304 stainless steel foils using micro-fabricated cantilevers
摘要： Aluminum nitride based (AlN-based) piezoelectric vibration energy harvesters (PVEHs) have been received much attention in the power generation for the device in microelectromechanical systems (MEMS). During the long-time vibration, PVEHs are suffering cyclically dynamic stress. This may result in the defect of the materials, and finally cause the failure of the device. To achieve a reliable design of the device that can work for a long time without failure, the investigation on the mechanical properties of Young’s modulus and fatigue were conducted for AlN films deposited on 304 stainless steel (SUS 304) foils in this study. Two kinds of materials were tested, SUS 304 foils with a thickness of 50 μm (SUS 304 (50 μm)) and a composite material of AlN films deposited on both sides of SUS 304 foils (AlN (1 μm)/ SUS 304 (50 μm)/ AlN (1 μm) structure). The samples were micro-fabricated to cantilevers. Young’s modulus was measured by the micro-cantilever resonance method. The resonant bending fatigue testing method was used to investigate the fatigue properties of the materials. The displacement amplitude of the samples was recorded during the tests. A new criterion by using the change of amplitude versus number of cycles was proposed to define the fatigue life. As results, the Young’s modulus was 184.9 and 342.9 MPa, for SUS 304 foil and AlN film, respectively. Stress-cycle (S-N) curves were plotted by using the proposed criterion successfully. The fatigue strength of SUS 304 foils and the material with AlN/ SUS 304/ AlN structure was estimated to be 294 and 327 MPa, respectively. Fatigue failures of stable crack, intrusions and extrusions, and slip bands, appeared on the surface of SUS 304 foils after the long time vibration. No fatigue failure or surface defect was observed on AlN films.
关键词： 304 stainless steel foil,aluminum nitride film,Young’s modulus,fatigue,micro-fabricated cantilever
更新于2025-09-23 15:21:01
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Modifying the thermomechanical properties of electrospun fibres of poly-vinyl cinnamate by photo-cross-linking
摘要： We explore the effects of cross-linking on some thermal and mechanical properties of polymer nanofibers of poly-vinyl cinnamate which were electro-spun from 1,2 dichloroethane. Scanning electron microscopy performed on the fibres revealed smooth fibres which were devoid of beading or ribbon-type features. When cross-linked, the Young’s moduli and glass transition temperatures of the fibres increase, owing to the formation of new covalent bonds which leads to higher overall binding energies. The glass transition temperatures increased by 20 K after 1 h of photo-polymerization while the Young’s modulus increased by 50% for the same exposure time. The glass transition temperatures as well as the heats of enthalpy indicate that a significant portion of cross-linking occurs within the first 10 min of exposure.
关键词： Photo-polymer,Young’s modulus,Enthalpy,Glass transition,Electro-spinning,Cross-linking
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Fill Factor Loss in Fielded Photovoltaic Modules Due to Metallization Failures, Characterized by Luminescence and Thermal Imaging
摘要： During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young’s modulus was calculated and its radial pro?le was correlated to the corresponding burnup pro?le and to the hardness radial pro?le data obtained by Vickers micro-indentation
关键词： Nuclear fuels,piezoelectric devices,Vickers microhardness,Young’s modulus,nuclear power
更新于2025-09-19 17:13:59