33 results
Search Results
2. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2.
- Author
-
Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Subjects
- *
BAND gaps , *OPTICAL properties , *MONOMOLECULAR films , *ELECTRONIC spectra , *DIELECTRIC function , *DENSITY functional theory , *ENERGY bands - Abstract
Context: The electronic properties and optical properties of Cr-doped monolayer WS2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1(ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2.
- Author
-
Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Subjects
BAND gaps ,OPTICAL properties ,MONOMOLECULAR films ,ELECTRONIC spectra ,DIELECTRIC function ,DENSITY functional theory ,ENERGY bands - Abstract
Context: The electronic properties and optical properties of Cr-doped monolayer WS
2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1 (ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
4. Analysis of the wall thickness distortion in tube hydro-forging.
- Author
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Chen, Gang, Chu, Guan-nan, Liu, Peixing, and Gao, Jun
- Subjects
SURFACE defects ,SURFACE phenomenon ,BENDING moment ,TUBES ,HYDROELECTRIC power plants ,POWER plants - Abstract
The tensile deformation is the most common forming principle in the sheet forming process, but there is a new tube forming process—tube hydro-forging has been developed based on the principle of compression deformation. In addition to the instability problem, a new surface defect—thickness distortion—was found in the compression deformation. In this paper, the wall thickness distortion is analyzed from the point of view of mechanics and deformation. It is revealed that in the low pressure tube hydroforming process, a bending moment exists and leads to some small wrinkles in the straight wall. In the tube hydro-forging, the small wrinkles would develop to the thickness distortion with the increase of compressive deformation. The wall thickness and compressive strain are two major effect factors. It is verified by experiments and simulation. This study helps to recognize the new surface phenomenon in compressive deformation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2
- Author
-
Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Published
- 2024
- Full Text
- View/download PDF
6. Compression properties of cost-efficient porous expanded clay reinforced AA7075 syntactic foams fabricated by industrial-oriented die casting technology.
- Author
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Cem Akgün, İsmail, Bolat, Çağın, and Gökşenli, Ali
- Subjects
DIE castings ,FOAM ,HEAT treatment ,CLAY ,ALUMINUM foam ,SISAL (Fiber) - Abstract
In today's manufacturing industries, hard competition between rival firms makes it compulsory for researchers to design lighter and cheaper machine components due to the megatrends of cost-effectiveness and anti-pollution. At this point, aluminum syntactic foams (ASFs) are new-generation engineering composites and come into the upfront as a problem-solver. Owing to their features like low density, sufficient elongation, and perfect energy absorption ability, these advanced foams have been considerably seductive for many industrial sectors nowadays. In this study, an industrial-oriented automatic die casting technology was used for the first time to manufacture the combination of AA7075/porous expanded clay (PEC). Micro evaluations (optical and FESEM) reveal that there is a homogenous particle distribution in the foam samples, and inspections are compatible with the other ASF studies. Additionally, T6 aging heat treatment was operated on one half of the produced foams to explore the probable impact of aging on the compressive responses. Attained results show that PEC particles can be an alternative to expensive hollow spheres used in the previous works. Besides, a favorable relationship is ascertained between the aging treatment and mechanical properties such as compression strength and plateau strength. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Compression properties of cost-efficient porous expanded clay reinforced AA7075 syntactic foams fabricated by industrial-oriented die casting technology
- Author
-
Akgün, İsmail Cem, Bolat, Çağın, and Gökşenli, Ali
- Published
- 2024
- Full Text
- View/download PDF
8. Coupling effect of feature size and δ phase on compressive deformation of a nickel-based superalloy at the mesoscopic scale
- Author
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Qiang Zhu, Dong Luan, Kai Yang, Guohua Fan, Heyong Qin, and Peng Zhang
- Subjects
Nickel-based superalloy ,Compressive deformation ,Size effect ,Constitutive model ,Mesoscopic scale ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Nickel-based superalloys have become essential materials due to their excellent comprehensive properties as the miniaturization of products in the aerospace and energy fields develops. The complex microstructure and various strengthening mechanisms of nickel-based superalloys make the plastic deformation behavior extremely complicated at the mesoscopic scale. In this paper, compression experiments of nickel-based superalloy samples with different feature sizes (i.e. the sample diameter to grain size ratio, D/d) and different aging times at the mesoscopic scale were carried out. The coupling effect of feature size and δ phase on the compressive deformation behavior was studied. The results show that the δ phase plays a role in precipitation strengthening during compressive deformation at the mesoscopic scale. When D/d is in the range of 9.7–10.9, the flow stress decreases significantly with the increase of grain size, and a “smaller is weaker” size effect appears. When D/d is less than 9.7, the flow stress increases with the grain size, and a “smaller is stronger” size effect appears. Considering grain boundary strengthening, solid solution strengthening, and precipitation strengthening, a size effect model of flow stress was established. The calculated values were in good agreement with the experimental values. The inhomogeneity of the end surface and side surface increases with the decrease of feature size and the decrease of aging time. The presence of the δ phase reduces the inhomogeneous deformation of nickel-based superalloys during compressive deformation at the mesoscopic scale.
- Published
- 2023
- Full Text
- View/download PDF
9. Mechanical behavior, damage mode and mechanism of AlSi10Mg porous structure manufactured by selective laser melting.
- Author
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Cai, Xuanming, Pan, Chenglong, Wang, Junyuan, Zhang, Wei, Fan, Zhiqiang, Gao, Yubo, Xu, Peng, Sun, Heyang, Li, Jun, and Yang, Wenshu
- Subjects
- *
SELECTIVE laser melting , *STRAIN hardening , *STRAIN rate , *COMPRESSION loads , *POROUS metals , *DUCTILE fractures - Abstract
• Bearing capacity and energy absorption characteristics of the optimized AlSi10Mg structure are significantly enhanced. • Finite element calculation model used in this paper accurately describes the mechanical behavior of AlSi10Mg structure. • Fracture features of AlSi10Mg porous structure indicate a ductile as well as a brittle failure under compressive load. • Normalized energy absorption helps designers select the one structure most suitable for a given application. In order to correctly understand the mechanical behavior, damage mode and damage mechanism of AlSi10Mg optimized structure under compressive load, a series of experimental and simulation studies were carried out. The stress-strain response, bearing capacity, energy absorption characteristics, damage mode and mechanism of the structure are analyzed and discussed. The results show that AlSi10Mg porous structure has obvious strain hardening effect, but no obvious strain rate effect. The volume fraction of AlSi10Mg porous structure increased from 9.43% to 22.15%, and its bearing strength increased from 22.34 MPa to 50.98 MPa. The optimized design structure is complex in this paper, which eliminates undesirable failure modes, and the benefit of high specific energy absorption is retained. The experimental and simulation results show that shear failure is the main cause of structural damage, and the normal of the failure section and the load action direction are roughly inclined at an angle of 45° ∼ 55°. The research results can provide an important reference for the optimal design of porous metal structure. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Fiber arrangement endow compression resistance of the mantis shrimp hammer-like appendage
- Author
-
Ming Wang, Lianze Ji, Shichao Niu, Jiayi Yang, Biao Tang, Jing Ni, Chun Shao, Xuefeng Zhang, and Xiao Yang
- Subjects
Biomaterials ,Chemical gradient ,Compressive deformation ,Fracture mechanism ,Bio-inspiration ,Mining engineering. Metallurgy ,TN1-997 - Abstract
For engineering materials, it is important to search for strategies to enhance certain combinations of mechanical properties, because many performances, such as strength and toughness, are mutually exclusive. Effective strategies have evolved in the biological tissues of many plants and animals to construct composite materials with unique combinations of mechanical properties. One impressive example is found in the hammer-like appendages of mantis shrimp, which are exceptionally resistant to crushing because they must withstand the reaction forces created when attacking prey. In this paper, quasi-static compression tests, advanced microscopic observation, and spectroscopic analysis were employed to identify a series of characteristic changes, including changes in mineral composition and arrangement of chitin fibers, and the resulting toughening mechanisms are also examined. The combination of experiments and finite element analysis revealed that by combining different fiber arrangements and components in adjacent macroscopic layers, longitudinal stress could be shifted to the lateral direction, hence efficiently enhancing longitudinal compression resistance while avoiding catastrophic failure. Overall, these findings further the understanding of the fiber structure and toughening mechanism of appendages, which may serve as a foundation for the development of tough bioinspired composites.
- Published
- 2022
- Full Text
- View/download PDF
11. Enhanced Electromagnetic Interference Shielding Effectiveness of an Eco-Friendly Cenosphere-Filled Aluminum Matrix Syntactic Foam.
- Author
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Thiyagarajan, Raja and Senthil Kumar, M.
- Subjects
ELECTROMAGNETIC interference ,ELECTROMAGNETIC shielding ,FOAM ,ALUMINUM ,ALUMINUM foam ,HARDNESS - Abstract
Electromagnetic interference (EMI) cause the equipments used in electronics and avionics industries to either deteriorate or malfunction. Therefore, EMI shielding is essential to ensure electronics equipment safety. The present investigation explores the EMI shielding effectiveness of micro-size cenosphere (2 wt.%, 4 wt.%, and 6 wt.%) filled aluminum matrix syntactic foams. The aluminum matrix syntactic foams were fabricated using stir-casting. The prepared samples were studied for their EMI shielding, microstructural characterization, compressive deformation behavior, and hardness. The cenosphere-filled aluminum syntactic foam exhibited better EMI shielding effectiveness, varied from −41.38 dB to −56.68 dB measured in the frequency range 8 to 12 GHz. This is due to microwave absorption and the dielectric nature of porous cenosphere fillers in the syntactic foam. The highest plateau strength 316.48 MPa and compressive yield strength of 289.53 MPa was achieved in 6 wt% cenosphere-filled syntactic foam. The microstructural study showed the presence of cenospheres in spherical form with homogeneous distribution. The observation shows good bonding between the matrix and cenosphere filler element. The micro-hardness measurement varied from 114 HV to 125.6 HV for the cenosphere filled syntactic foam (up to 4 wt %); further increasing the cenosphere wt% reduced the hardness. The XRD analysis showed the presence of reaction compounds AlSiO
2 , and Al2 SiO5 which enhanced the brittleness in the syntactic foams. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
12. Optimization of winding conditions considering web thickness variation in width direction and experimental verification
- Author
-
Hiromu HASHIMOTO and Yuta SUNAMI
- Subjects
web handling ,optimization ,wind-up tension ,thickness distribution ,in-roll stress ,compressive deformation ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
The webs such as paper, plastic film and thin metal are produced by Roll-to Roll manufacturing system, and are wound into a roll in the final process of this system. However, if the winding conditions of the web are inappropriate, the defects such as gage band, wrinkle and slippage will occur in wound roll, and then quality of products is significantly reduced. In previous studies, some analysis models of in-roll stress considering various factors, have been established to predict the defects. However, as far as authors know, there is few research regarding the gage band. In particular, the plastic films used for high functional flexible devices are being thinner, the defects can occur easily. In this paper, the in-roll stress analysis considering the web thickness variation in width direction and compressive deformation of web in the radial direction using the Hertz contact theory is presented. Moreover, optimization of winding conditions is conducted to prevent simultaneously the gage band, wrinkle and slippage. As a result, it was confirmed that the presented analysis can estimate the radial stress distribution of wound roll in the width direction. And, the effectiveness of optimized wind-up tension is verified theoretically and experimentally.
- Published
- 2015
- Full Text
- View/download PDF
13. Effects of compressive deformation of backfill materials on strata movement and stress evolution in deep gangue backfill mining.
- Author
-
Li, Meng, Peng, Yifan, Zhang, Jixiong, Zhu, Cunli, Ma, Dan, and Huang, Peng
- Abstract
The compressive deformation of backfill materials is large due to the large mining depth of coal seams and high mining-induced stress during the deep backfill mining. Therefore, the controlling effect on strata movement significantly differs from that in shallow coal seams. The research aims to explore the influences of the compressive deformation of backfill materials on the strata movement and stress evolution in deep backfill mining. For this purpose, the backfill panel in Xinjulong Coal Mine, Shandong Province, China was taken as an engineering case study; the changes in displacement, structural evolution, and stress distribution of overlying strata in the panel under compression ratios of backfill materials of 70%, 40%, and 20% were investigated. In addition, the influences of different compressive deformations of the backfill materials on the controlling effect on overlying strata were compared and investigated. The results showed that the displacement of overlying strata in the backfill panel decreases with the decreasing compression ratio: the maximum displacement of overlying strata decreases from 24.32 to 13.74 and 6.83 mm as the compression ratio is reduced from 70 to 40%, and 20%, respectively. Relative to the overlying strata at a compression ratio of 70%, the vertical displacements at compression ratios of 40 and 20% separately decrease by 43.5 and 71.9%. The lower the compression ratio of backfill materials, the better the control of overlying strata. The results provide theoretical support for optimizing the performance of backfill materials in deep backfill mines and controlling the ground pressure in the stope. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
14. Investigating the Width of Isolated Coal Pillars in Deep Hard-Strata Mines for Prevention of Mine Seismicity and Rockburst
- Author
-
Fuxing Jiang, Wang Bo, Jinhai Liu, Xiaoguang Shang, Sitao Zhu, and Xiufeng Zhang
- Subjects
Control and Optimization ,0211 other engineering and technologies ,Energy Engineering and Power Technology ,isolated coal pillar ,02 engineering and technology ,Induced seismicity ,limited deflection ,010502 geochemistry & geophysics ,Inner mongolia ,01 natural sciences ,lcsh:Technology ,mine seismicity ,Compressive deformation ,Mining engineering ,Coal ,microseismic monitoring ,Electrical and Electronic Engineering ,Engineering (miscellaneous) ,021102 mining & metallurgy ,0105 earth and related environmental sciences ,Microseism ,Renewable Energy, Sustainability and the Environment ,business.industry ,lcsh:T ,Coal mining ,compression ,rockburst ,business ,Geology ,Energy (miscellaneous) - Abstract
In deep mines, a reasonable design of the widths of isolated coal pillars (ICPs) is critically important, particularly for hard-strata mines. This is because the frequent occurrence of mine seismicity (MS) and rockburst in deep mines often arises from the inappropriate widths of the remnant ICPs. To address this problem, this paper takes the ICP of Yingpanhao Coal Mine in Inner Mongolia in China as the engineering case study and then presents a mechanical model to illuminate the occurrence mechanism of MS induced by the mining on both sides of ICPs. The results indicate that, after the mining on both sides of ICPs, the ICPs will produce a vertical compressive deformation, and the overlying high main key stratum (MKS) will experience a flexure deformation. When the limited deflection of MKS is less than the compression of ICPs, the MKS will be fractured, and the released energy may lead to MS. Based on the mechanism model, a design criterion is proposed for ICP widths, this criterion can effectively reduce the risk of the induced rockburst and MS. Then the occurrence mechanism of MS and the design basis for ICP width are verified by numerical simulation and field microseismic monitoring. The results in this paper may be used as a theoretical guidance for rational ICP design in deep mines and may help mitigate the risk of rockburst and MS from early mining stages.
- Published
- 2020
- Full Text
- View/download PDF
15. Optimization of winding conditions considering web thickness variation in width direction and experimental verification
- Author
-
Yuta Sunami and Hiromu Hashimoto
- Subjects
Engineering ,in-roll stress ,business.industry ,Structural engineering ,wind-up tension ,thickness distribution ,Web handling ,web handling ,Compressive deformation ,Variation (linguistics) ,compressive deformation ,TJ1-1570 ,Mechanical engineering and machinery ,business ,optimization - Abstract
The webs such as paper, plastic film and thin metal are produced by Roll-to Roll manufacturing system, and are wound into a roll in the final process of this system. However, if the winding conditions of the web are inappropriate, the defects such as gage band, wrinkle and slippage will occur in wound roll, and then quality of products is significantly reduced. In previous studies, some analysis models of in-roll stress considering various factors, have been established to predict the defects. However, as far as authors know, there is few research regarding the gage band. In particular, the plastic films used for high functional flexible devices are being thinner, the defects can occur easily. In this paper, the in-roll stress analysis considering the web thickness variation in width direction and compressive deformation of web in the radial direction using the Hertz contact theory is presented. Moreover, optimization of winding conditions is conducted to prevent simultaneously the gage band, wrinkle and slippage. As a result, it was confirmed that the presented analysis can estimate the radial stress distribution of wound roll in the width direction. And, the effectiveness of optimized wind-up tension is verified theoretically and experimentally.
- Published
- 2015
16. Phase composition of Ni-Al-Co-Me-based superalloy modified by deformation
- Author
-
Kozlov Eduard, Nikonenko Alisa, Popova Natalya, and Nikonenko Elena
- Subjects
Superalloy ,Compressive deformation ,Qualitative analysis ,Morphology (linguistics) ,Materials science ,Phase composition ,Metallurgy ,Deformation (engineering) - Abstract
The paper presents the investigations of Ni-Al-Co-Me-based superalloy using TEM and SEM techniques. The structure and phase composition of the superalloy are investigated and the volume fractions and morphology of phases are determined in this paper. These investigations include the quantitative and qualitative analysis. It is shown that 70% compressive deformation of superalloy at 1200°C modifies its structure and phase composition.
- Published
- 2017
17. COMPRESSIVE DEFORMATION CHARACTERISTICS OF CRUSHED SANDSTONE BASED ON MULTIPLE EXPERIMENTAL FACTORS.
- Author
-
YANAN SUN, PEISEN ZHANG, WEI YAN, FENQIAN YAN, and JUNDA WU
- Subjects
SEEPAGE ,SANDSTONE ,CYCLIC loads ,SLIDING friction ,EXPONENTIAL functions ,TEST systems - Abstract
In this study, the compressive deformation of crushed sandstone was tested using a crushed rock deformation-seepage test system, and the effects of various factors, including crushed rock grade, grade combination, water saturation status, and stress loading method (i.e., continuous loading or cyclic loading and unloading), on the compressive deformation of crushed sandstone was analyzed from four perspectives including stress-strain, bulking coefficient, deformation mechanism and energy dissipation. The results indicate that the stress-strain relations of crushed sandstone are closely associated with all factors considered, and are well represented by exponential functions. The strain observed for a given applied stress increased with increasing crushed rock grade throughout the loading period. Crushed sandstone grades were combined according to a grading index (n), where the proportion of large-grade rocks in the sample increased with increasing n. The bearing capacity of a water-saturated crushed sandstone sample with n = 0.2 was less than that of an equivalent dry sample for a given applied stress. The stress-strain curve of a water-saturated crushed sandstone sample with n = 0.2 under cyclic loading and unloading was similar to that obtained under continuous loading. Observation and discovery, the deformation mechanism of crushed sandstone was mainly divided into four stages, including crushing, rupture, corner detachment and corner wear. And 20% of the work done by testing machine is used for friction between the crushed sandstone with the inner wall of the test chamber, and 80% is used for the closing of the void between the crushed sandstone, friction sliding, crushing damage. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
18. Influence of pulsive pressure waves on liquid penetration into wood in semi-opened container
- Author
-
Kozo Kanayama, Tsunehisa Miki, Masako Seki, Soichi Tanaka, and Kenji Umemura
- Subjects
0106 biological sciences ,Materials science ,0402 animal and dairy science ,Pressure-wave treatment ,04 agricultural and veterinary sciences ,Penetration (firestop) ,Aspirated pit ,Hydraulic pressure ,040201 dairy & animal science ,01 natural sciences ,Tyloses ,lcsh:TH1-9745 ,Biomaterials ,Compressive deformation ,Permeability of wood ,Liquid penetration ,Impregnation of wood ,010608 biotechnology ,Cavitation ,Collapse of wood ,lcsh:SD1-669.5 ,Irradiation ,lcsh:Forestry ,Composite material ,lcsh:Building construction - Abstract
The purpose of this paper was to confirm the influence of pulsive pressure waves on the liquid penetration into wood in the semi-opened container. Wood block sample was irradiated by the pulsive pressure waves in the semi-opened container filled with water used as a liquid. The irradiation was also performed in the closed container for the comparison. The water penetration into the sample was promoted by the pressure-wave irradiation. There was little difference in the degree of the penetration between the closed and the semi-opened containers. It was presumed from the measured hydraulic pressure that the pressure-wave energy irradiated on the sample in the closed container was higher than that in the semi-opened container. It was also presumed that the cavitation generation was promoted in the semi-opened container. This indicates that the cavitation as well as the pressure waves themselves affected the liquid penetration into wood. The compressive deformation of the sample irradiated in the semi-opened container was slightly smaller than that in the closed container. This indicates that the pulsive pressure-wave irradiation in the semi-opened container promoted the liquid penetration into wood with less compressive deformation.
- Published
- 2019
19. Anisotropic springback models of FCC metal material under severe plastic compressive deformation
- Author
-
Huiping Li, Hongli Hou, Liang Chen, and Guoqun Zhao
- Subjects
Work (thermodynamics) ,Materials science ,Mechanical Engineering ,Forming processes ,Condensed Matter Physics ,Metal ,Bulk forming ,Stress (mechanics) ,Compressive deformation ,Mechanics of Materials ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,Severe plastic deformation ,Composite material ,Anisotropy ,Civil and Structural Engineering - Abstract
Accurate prediction of springback under severe plastic deformation is necessary for the geometric error in precision forming process, in order to establish accurate model of saturated springback under bulk forming. In this paper, the springback behavior and prediction model of anisotropic face-centered cubic (FCC) crystal copper alloy under severe plastic compressive deformation (SPCD) were studied from micro-perspective and macro-perspective. From the micro-perspective, a mathematical model of springback was established based on physical and mechanics mechanisms for predicting the saturated springback of the SPCD. Subsequently, from the macro-perspective, the effects of the macro variables including stress, strain, applied load, deformed surface area, external work, etc., on the saturated springback of quasi-static SPCD were discussed, and a anisotropic springback model of FCC material for the quasi-static SPCD process in a Gaussian form was set up based on above discussion and the expression of the proposed mathematical model of springback. Furthermore, the non-quasi-static anisotropic springback model containing comprehensive effect factor and size effect factor was proposed to predict the saturated springback of copper alloy after rolling process. The results indicated that the proposed springback models based on physical mechanism and macro variables can accurately predict the saturated springback of the anisotropic copper alloy under the SPCD. By introducing comprehensive effect and size effect factors, the anisotropic springback model for the non-quasi-static SPCD process has higher accuracy in predicting the saturated springback of bulk forming process. The present study revealed the springback behavior of anisotropic FCC copper alloy, and proposed accurate prediction models of saturated springback, which are of great significance to adjust the forming process and compensate the springback error of the FCC metal material during the bulk forming process.
- Published
- 2021
20. Characterization of Geometrical Changes of Spherical Advanced Pore Morphology (APM) Foam Elements during Compressive Deformation
- Author
-
Zoran Ren, Matej Vesenjak, Ken Shimojima, Matej Borovinšek, and Yoshikazu Higa
- Subjects
Morphology (linguistics) ,Materials science ,APM foam ,02 engineering and technology ,Structural geometry ,geometrical analysis ,lcsh:Technology ,01 natural sciences ,Article ,Compressive deformation ,compression loading ,0103 physical sciences ,General Materials Science ,Composite material ,lcsh:Microscopy ,Porosity ,lcsh:QC120-168.85 ,010302 applied physics ,lcsh:QH201-278.5 ,lcsh:T ,Micro computed tomography ,021001 nanoscience & nanotechnology ,micro computed tomography ,Characterization (materials science) ,Compressive load ,porosity analysis ,lcsh:TA1-2040 ,Digital image analysis ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 - Abstract
The mechanical properties of Advanced Pore Morphology (APM) foam elements depend strongly upon their internal porous and external structural geometry. This paper reports on a detailed investigation of external (e.g. shape and size) and internal (e.g. distribution, size, number of pores) geometry and porosity changes of APM foam elements, during compressive loading by means of the ex-situ micro-Computed Tomography, and advanced digital image analysis and recognition. The results show that the porosity of APM foam elements decreases by only 25% at the engineering strain of 70% due to an increase of the number of pores at high stages of compressive deformation. The APM foam elements also exhibit a positive macroscopic Poisson&rsquo, s ratio of &upsilon, = 0.2, which is uncharacteristic for cellular structures.
- Published
- 2019
21. Thermo-mechanical treatments of Sc- and Mg-modified Al–Cu alloy welds
- Author
-
Koteswara Rao, S. R., Kamsala Devi, B., Sreenivasa Rao, K., and Prasad Rao, K.
- Published
- 2009
- Full Text
- View/download PDF
22. Effects of mechanical deformation and annealing on the microstructure and hardness of Pb-free solders
- Author
-
Lauro, Paul, Kang, Sung K., Choi, Won Kyoung, and Shih, Da-Yuan
- Published
- 2003
- Full Text
- View/download PDF
23. Tool path strategies and deformation analysis in multi-pass incremental sheet forming process
- Author
-
Yanle Li, Paul A. Meehan, and Zhaobing Liu
- Subjects
Computer science ,business.industry ,Mechanical Engineering ,Process (computing) ,Structural engineering ,Deformation (meteorology) ,Industrial and Manufacturing Engineering ,Finite element method ,Computer Science Applications ,Material flow ,Compressive deformation ,Control and Systems Engineering ,Fracture (geology) ,Formability ,business ,Software ,Incremental sheet forming ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
Incremental sheet forming (ISF) is a new promising manufacturing technology with high potential to shape complex three-dimensional parts by using a relative small tool. However, ISF is presently limited due to non-uniform thickness distribution of formed parts, especially excessive thinning on severely sloped regions. This typically leads to fracture and hence limits process formability. This paper aims to tackle this issue by developing appropriate tool path strategies for multi-pass deformation design in ISF. More specifically, two more complex shapes are designed to validate the proposed multi-pass deformation design methodology by finite element simulations and experiments. The interactions of different tool path strategies on material thinning of the final part are evaluated in terms of process formability and thickness strain distribution given the same multi-pass design. Furthermore, the movement of material points is traced to explain the material flow mechanism in multi-pass forming compared to single-pass forming. It is concluded that both deformation passes (intermediate shapes) and tool path generation strategies would influence the thickness strain distribution as well as process formability. Appropriate tool paths should be devised to further reduce material thinning and improve the process formability by taking the geometrical features of the designed part into account. Additionally, the proposed multi-pass deformation design enables sufficient material to flow into the deformed region from the outside region so as to allow a compressive deformation state to develop and steeper shapes to be formed.
- Published
- 2014
24. Strengthening and Thermally Activated Processes in an AX61/Saffil Metal Matrix Composite.
- Author
-
Trojanová, Zuzanka, Száraz, Zoltán, Lukáč, Pavel, Drozd, Zdeněk, and Džugan, Ján
- Subjects
METALLIC composites ,STRESS relaxation tests ,SQUEEZE casting ,DISLOCATION density ,STRESS relaxation (Mechanics) ,MAGNESIUM alloys - Abstract
AX61 magnesium alloy was reinforced with short Saffil fibres using squeeze cast technology. Samples were cut from the casting in two directions: parallel and perpendicular to the fibre plane. Samples were deformed in compression at various temperatures from room temperature to 300 °C. Various strengthening mechanisms such as load transfer, increased dislocation density, Orowan and Hall–Petch strengthening were analysed. During deformation, the stress relaxation tests were subsequently performed. The relaxation curves were evaluated with respect to Li and Feltham equations with the aim to find stress components in matrix and parameters of the thermally activated process(es). [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
25. Investigation on Compressive Formability and Microstructure Evolution of 6082-T6 Aluminum Alloy.
- Author
-
Xu, Zhouli, Ma, Huijuan, Zhao, Ning, and Hu, Zhili
- Subjects
ALUMINUM alloys ,HEAT treatment ,LOW temperatures ,HIGH temperatures ,BIOLOGICAL evolution - Abstract
The 6xxx aluminum alloy is the first choice for automotive lightweight forgings due to its excellent performance, high strength and low weight. The production time of current aluminum alloy forging generally exceeds 10 h. To reduce the production time of traditional aluminum alloy forgings, 6082-T6 aluminum alloy is used in the forming process. The effects of different heating temperatures (200 °C, 300 °C, and 400 °C) and deformation degrees (30%, 50%, and 70%) on the deformability and properties of 6082-T6 billets have been investigated. The results show that when the heating temperature is higher than 300 °C, the compressive deformation resistance obviously decreases with increasing strength. With compression at 200 °C and 70% deformation with short heating time, the strength of the sample is close to the T6 (solution treatment and artificial aging) state. A large number of dislocations and subgrains were introduced due to the compression deformation, and their amounts decreased as the heating temperature increased. The size of the precipitated phase β′′ slightly grows under a heating temperature of 200 °C. However, when the heating temperature is higher than 300 °C, the precipitated phase gradually changes from β′′, which is optimal for the strengthening effect, to β′ and β, which offer weaker strengthening. Therefore, under a lower heating temperature of 200 °C for 5 min, a large number of dislocations are introduced with the β′′ precipitated phase, leading to higher strength with less heat treatment time. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
26. Comparative Study of Hot Deformation Behavior and Microstructure Evolution of As-Cast and Extruded WE43 Magnesium Alloy.
- Author
-
Kang, Yuehua, Huang, Zhenghua, Zhao, Hu, Gan, Chunlei, Zhou, Nan, Zheng, Kaihong, Zhang, Jing, Pan, Fusheng, Huang, J.C., and Wang, Shuncheng
- Subjects
MAGNESIUM alloys ,MICROSTRUCTURE ,RARE earth metal alloys ,RARE earth metals ,STRAIN rate ,CRYSTAL grain boundaries ,COMPARATIVE studies - Abstract
Under compressive testing at 400 °C and a strain rate range of 0.05–5 s
−1 , the hot deformation behavior and microstructure evolution of an as-cast (AC), as-extruded (with a bimodal grain structure (named as Ex-1) or a relatively uniform fine grain structure (Ex-2)) WE43 alloy have been investigated and compared. The results indicate that the AC sample exhibits the highest peak stress, while the Ex-2 sample has the lowest value. Within the AC material, fine grains were firstly formed along the pancake-like deformed grains (as a necklace structure). The necklace structure was also formed within the Ex-1 and Ex-2 materials at high strain rates of 0.5 and 5 s−1 . However, a lamellar structure that the coarse elongated grains divided by parallel boundaries was formed within the Ex-1 material. A relatively more homogeneous fine grain structure is achieved after a true strain of 1.0 within the Ex-2 material at a low strain rate of 0.05 s−1 . In addition, a discontinuous dynamic recrystallization mechanism by grain boundary bulging is found to occur. After a true strain of 1.2, a (0001) fiber texture, a typical rare earth (RE) texture, and a relatively random texture are formed within the AC, Ex-1, and Ex-2 WE43 alloy material, respectively. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
27. Simulation on microscopic deformation behavior of engine gasket
- Author
-
Ke Cao, Yixi Zhao, and Sun Jin
- Subjects
Compressive deformation ,Engineering drawing ,Materials science ,Volume (thermodynamics) ,lcsh:TA1-2040 ,Gasket ,Head (vessel) ,Head gasket ,Polygon mesh ,Composite material ,Combustion chamber ,Deformation (meteorology) ,lcsh:Engineering (General). Civil engineering (General) - Abstract
Engine gasket is the thin steel plate with coatings. Its compressive deformation affects the height of engine assembly, which changes combustion chamber’s volume and then influences engine performance. In this paper, the assembly simulation of head, block and gasket was studied. Then a further simulation takes the thin coatings on steel sheet into consideration. In the second simulation, gasket’s partial micro-model in micron-scale meshes was established and deformation of coatings was analysed. The combination of deformations explores the cause of fluctuations of gasket’s tightened thickness and obtains more precise numerical results of tightened thickness at different positions. Moreover, a lead pellet test was carried out to verify the results of tightened thickness calculation.
- Published
- 2016
28. Analysis of the Influence Factors of Differential Settlement of High Embankment in Mountain Area
- Author
-
Yuanming Dou and Min Geng
- Subjects
geography ,Compressive deformation ,Road engineering ,geography.geographical_feature_category ,Consolidation (soil) ,Modulus ,Geotechnical engineering ,Bearing capacity ,Levee ,Geology - Abstract
This paper reveals and analyses various influence factors which cause differential settlement of high embankment in mountain area using indoor consolidation test and field loading test. In this research, the actual stress characteristics of high embankment are simplified, stability compression value of stuffing with loads under lateral restricted conditions can be measured, e-p curves and p-s curves are drawn, we can calculate compression modulus as computation criteria to estimate the settlement of high embankment. The results indicate that unconsolidated flow of high embankment is the main factor to cause differential settlement of high embankment in mountain area. As the soil consolidated, compressive deformation and the strength gradually increase, the bearing capacity of the foundation is enhanced to reduce differential settlement of the post-construction of high embankment.
- Published
- 2012
29. AN EXPERIMENTAL STUDY ON THE STRESS TRANSFER IN MORTISE-TENON JOINTS FOR WOODEN FRAME STRUCTURES
- Author
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Toku Nishimura, Yoshiyuki Suzuki, and Masami Goto
- Subjects
Engineering ,business.industry ,Mortise and tenon ,Building and Construction ,Structural engineering ,Compressive deformation ,Discontinuity (geotechnical engineering) ,Energy absorbing ,Architecture ,Perpendicular ,Restoring force ,Composite material ,business ,Static loading - Abstract
In this paper, results of static loading tests on the stress transfer in mortise-tenon joints are shown. With the investigations of the experimental results, we present key requirements of a mechanical model for stress transfer in tenon joints. The model considers the discontinuity as the results of bi-axial stress state and friction by contact between tenon and mortice. Then the model can be evaluated stress transfer in the directions along fiber and perpendicular to fiber. It is necessary to recognize energy absorbing capacity and strength, inelastic mechanical model should simulate the compressive deformation inclined to the grain, the resistance of cotter and splitting. The mechanical model of main frames should be dealt with geometrically and material non-linearity incorporated with restoring force produced by rocking.
- Published
- 2010
30. In-Plane Compressive Deformation of Honeycomb Structure in Consideration of Work-Hardening Effect (1st Report, Numerical Investigation)
- Author
-
Takuya Ogawa, Shingo Ozaki, and Dai-Heng Chen
- Subjects
Compressive deformation ,In plane ,Honeycomb structure ,Materials science ,Buckling ,Deformation mechanism ,Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Unit model ,Work hardening ,Composite material ,Finite element method - Abstract
In this paper, the crushing behaviour of hexagonal honeycomb structures with finite widths and heights subjected to in-plane compressive loading is studied by using the finite element method. It is found that stress-strain curves are clasiffied roughly into two types, which include both symmetric and asymmetric modes. They are influenced by ratio of thickness of cell wall, ratio of the work-hardening, and ratio of the yield stress. In addition, it is revealed that the deformation mechanism of the honeycomb structure with the finite width and the height can be explained by the unit model proposed by Klintworth (1988), even if the effect of the work-hardening is considered.
- Published
- 2008
31. Ultra-Light Reduced Graphene Oxide Based Aerogel/Foam Absorber of Microwave Radiation.
- Author
-
Plyushch, Artyom, Kuzhir, Polina, Zhai, Tianliang, Xia, Hesheng, Santillo, Chiara, Verdolotti, Letizia, and Lavorgna, Marino
- Subjects
GRAPHENE oxide ,AEROGELS ,MICROWAVE radiometers ,URETHANE foam ,ELECTROMAGNETIC interference - Abstract
We present the polarization-dependent highly absorptive in Ka-band composition of conventional polyurethane foam filled with in situ synthesized aerogel coated by reduced graphene oxide (rGO). The rGO-based aerogel was in situ prepared into the open-cell polyurethane foam (PUF) skeleton through a bidirectional freeze-drying process. The aerogel is composed of the flat lamellas stacks, possessing the anisotropic structure and unique electromagnetic properties. Further improvement of the electromagnetic shielding ability was possible by the rGO coating introduction as a coupling layer between PUF and rGO-based aerogel. This enhances the overall conductivity of the resulting composites: 1.41 + 3.33i S/m vs. 0.9 + 2.45i S/m for PUF loaded with in situ synthesized aerogel without rGO coating.With this mechanically robust plane easy to process coating one could achieve −20 dB by power with the record light structure (0.0462 g/cm
2 ). That could compete in view of the weight per cm2 even with graphene-based absorbers comprising either dielectric matching elements or back metal reflectors, or both. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
32. Evaluation of Circle Diameter by Distributed Tactile Information in Active Tracing
- Author
-
Fumio Kojima, Hiroyuki Nakamoto, and Futoshi Kobayashi
- Subjects
Engineering ,Article Subject ,Active touch ,business.industry ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) ,Robotic hand ,Process (computing) ,Tracing ,Object (computer science) ,Compressive deformation ,Control and Systems Engineering ,lcsh:Technology (General) ,lcsh:T1-995 ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,business ,Instrumentation ,Image resolution ,Simulation ,Tactile sensor - Abstract
Active touch with voluntary movement on the surface of an object is important for human to obtain the local and detailed features on it. In addition, the active touch is considered to enhance the human spatial resolution. In order to improve dexterity performance of multifinger robotic hands, it is necessary to study an active touch method for robotic hands. In this paper, first, we define four requirements of a tactile sensor for active touch and design a distributed tactile sensor model, which can measure a distribution of compressive deformation. Second, we suggest a measurement process with the sensor model, a synthesis method of distributed deformations. In the experiments, a five-finger robotic hand with tactile sensors traces on the surface of cylindrical objects and evaluates the diameters. We confirm that the hand can obtain more information of the diameters by tracing the finger.
- Published
- 2013
- Full Text
- View/download PDF
33. Interlaminar strength test of glass cloth laminated plastics under combined stress
- Author
-
Kozo Ikegami and Masahiro Funabashi
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Structural engineering ,Condensed Matter Physics ,Finite element method ,Stress (mechanics) ,Compressive deformation ,Mechanics of Materials ,Thin wall ,embryonic structures ,Ultimate tensile strength ,Fracture (geology) ,General Materials Science ,Deformation (engineering) ,Tube (container) ,Composite material ,business - Abstract
This paper presents a testing method of interlaminar strength in the laminated direction of glass cloth reinforced plastics. To obtain the mechanical properties in the laminated direction, a method using the laminated thin wall tube specimens was proposed. The stress distribution in the specimen under tensile load was analyzed by using the finite element method. The shape of the specimen having a flat tensile stress distribution was numerically searched by varying the dimensions of specimen. The strain distribution calculated by the finite element method was confirmed by tensile tests of the laminated thin wall tube specimens. The interlaminar strength tests were conducted by subjecting the laminated specimens to axial, torsional and combined loads.The deformation in the laminated direction showed nearly elastic behavior up to the fracture of specimens except the case of compressive deformation. The interlaminar strength of the specimens under combined stress was approximately expressed by Hoffman's fracture criterion.
- Published
- 1984
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