In order to provide technical supports for designing a new type of spiral plate forming machine, FEM analysis and simulation were carried out based on pressing tests. Deformation, stress distribution, residual stress ...In order to provide technical supports for designing a new type of spiral plate forming machine, FEM analysis and simulation were carried out based on pressing tests. Deformation, stress distribution, residual stress and spring back of the spiral plate were calculated. Relationships between the spiral pitch to inclination angle of the punch and die, material properties and thickness of the plate were analyzed. A data converter was developed and effectively used in the analysis. The results of FEM analysis and simulation have been applied to design the spiral plate forming machines.展开更多
Springs are vital freshwater sources for rural communities,yet they are increasingly threatened by nutrient enrichment,microbial contamination,and declining ecological integrity.This study assessed the water quality o...Springs are vital freshwater sources for rural communities,yet they are increasingly threatened by nutrient enrichment,microbial contamination,and declining ecological integrity.This study assessed the water quality of Sumber Suko Spring in East Java,Indonesia,through an integrated ecological approach combining physicochemical,microbiological,biological,and hydrological parameters across wet and dry seasons.Physicochemical results showed stable temperature(24.1–26.7°C),near-neutral pH(6.4–6.9),and adequate dissolved oxygen(6.2–7.4 mg/L).However,nitrate concentrations were elevated(39.37–48.16 mg/L),exceeding natural background levels and indicating agricultural leaching,while phosphate values ranged between 0.12–0.21 mg/L.Microbial analysis revealed high total coliform counts(24 CFU/100mL),far above WHO standards,although E.coli was not detected.Plankton analysis identified 10 genera,with Microcystis aeruginosa dominating,particularly in the dry season,signaling risks of eutrophication.Shannon-Wiener diversity indices(H’)ranged from 1.25 to 1.67,with evenness values between 0.43 and 0.56,reflecting low-to-moderate community stability.Hydrological measurements showed seasonal discharge fluctuations from 14.6 L/s in the wet season to 7.8 L/s in the dry season,strongly correlated with rainfall.Overall,the integration of nutrient enrichment,coliform contamination,and cyanobacterial dominance indicates that Sumber Suko Spring is under ecological stress and does not meet drinking water standards without treatment.The findings highlight the urgent need for source protection,disinfection,and continuous monitoring within a water safety plan framework.This study provides evidence-based insights to support local policy alignment with WHO guidelines and emphasizes the importance of community participation in sustaining spring ecosystems for long-term water security.展开更多
The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the ...The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the electrodes and the propellant. The effects of spring pressure on the ignition and combustion of propellants have not yet been studied. In this paper, a universal testing machine and an electrochemical workstation were firstly utilized to investigate the compressive mechanical property and conductivity of Hydroxylamine Nitrate(HAN)-ECSP. The maximum pressure at which the propellant undergoes elastic deformation is 65 kPa. When the spring pressure increased from 5.1 k Pa to 20.4 kPa, the propellant resistance decreased from 56.8 Ω to 36.8 Ω.Various observation methods were employed to study the process of electrical energy injection and the ignition and combustion characteristics under constant voltage. Appropriately increasing the spring pressure can accelerate the injection of electrical energy into the propellant, increase the electrification current, and thus reduce the initial ignition delay time of the propellant. When the spring pressure is 20.4 kPa, the squeezing speed of the propellant is too fast, making it difficult for the propellant to be adequately heated at the electrode interface, which is unfavorable for ignition. Excessive spring pressure also leads to the accumulation of a large amount of combustion residue on the electrode plate, hindering the mixing and diffusion of hot gases during the second ignition process, preventing the gaseous flame of the propellant. When the spring pressure is 5.1 kPa, improving the working voltage can enhance the repeated ignition characteristics of the propellant.展开更多
Self-Centering Piston-Based Braced Frames(SC-PBBFs)are designed to curtail structural damage under severe ground motions.The self-centering mechanism in this bracing mitigates structural damage during an earthquake,th...Self-Centering Piston-Based Braced Frames(SC-PBBFs)are designed to curtail structural damage under severe ground motions.The self-centering mechanism in this bracing mitigates structural damage during an earthquake,thereby reducing post-earthquake repair costs and contributing to seismic resilience.However,non-structural components,particularly those sensitive to floor acceleration,remain vulnerable,resulting in prolonged func-tional recovery times.This paper aims to address this limitation by introducing a novel structural archetype,the Self-Centering Viscous-Based Braced Frame(SC-VBBF),which integrates superelastic shape memory alloy(SMA)bars,viscous dampers(VDs),and friction springs(FSs).A streamlined analytical approach relies on the strength decoupling of VD from other components using aλfactor to design SC-VBBFs.To evaluate the effectiveness of the hybrid brace,a set of 4-,8-,and 12-story archetypes equipped with SC-PBBs and SC-VBBFs are simulated in OpenSees and analyzed under various earthquake types,including crustal,subcrustal,and subduction events.The results demonstrate the superior performance of the SC-VBBF withλ≤0.5 system compared to SC-PBBFs in mitigating floor accelerations under design-level earthquakes and improving seismic resilience.展开更多
The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 alu...The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and forming time on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method （FEM） analysis.展开更多
In recent years, the use of advanced high strength steels in automotive industry has been increased remarkably. Among advanced high strength steels, dual phase （DP） steels have gained a great attention owing to a co...In recent years, the use of advanced high strength steels in automotive industry has been increased remarkably. Among advanced high strength steels, dual phase （DP） steels have gained a great attention owing to a combination of high strength and good formability. However, high strength usually increases the spring-back behavior of the material, which creates problems for the parts during the assembly. Thus, the uniaxial tensile deformation and spring-back behaviors of DP600 advanced high strength steel were investigated in rolling （0°）, diagonal （45°） , and transverse （90°） directions in the temperature range from room temperature （RT） to 300 ℃. All tests were performed at a deformation speed of 25 mm/min. A V-shaped die （60°） was used for the spring-back measurements. The results indicated that the formability and spring-back of the material were decreased with increasing the temperatures. The material showed complex behaviors in different directions and at different temperatures.展开更多
The spring-back of a bending metal tube was studied through extensive experiments and finite element method （FEM） analysis. An approximate equation for the spring-back angle of bending was deduced. It is noted that ...The spring-back of a bending metal tube was studied through extensive experiments and finite element method （FEM） analysis. An approximate equation for the spring-back angle of bending was deduced. It is noted that the mechanical properties of the material （in a tubular form） are quite different from those found in the standard tensile tests （when the materials are in bar forms）. This is one of the major reasons that result in the discrepancies in the outcomes of experimental study, FEM calculations, and spring-back analysis. It is therefore of crucial importance to study the mechanical properties of the materials in their tubular forms. The experiments and FEM simulations prove that the spring-back angle is significantly affected by the mechanical properties of the materials. The angle decreases accordingly with plastic modulus, but changes inversely with the hardening index and elastic modulus The spring-back angle is also affected by the conditions of tube deformation： it increases accordingly with the relative bending radius but changes inversely with the relative wall thickness. In addition, the spring-back angle increases nonlinearly with the bending angle.展开更多
基金Supported by the New-Cooperation Project of Japan Ministry of Economy,Trade and Industry
文摘In order to provide technical supports for designing a new type of spiral plate forming machine, FEM analysis and simulation were carried out based on pressing tests. Deformation, stress distribution, residual stress and spring back of the spiral plate were calculated. Relationships between the spiral pitch to inclination angle of the punch and die, material properties and thickness of the plate were analyzed. A data converter was developed and effectively used in the analysis. The results of FEM analysis and simulation have been applied to design the spiral plate forming machines.
文摘Springs are vital freshwater sources for rural communities,yet they are increasingly threatened by nutrient enrichment,microbial contamination,and declining ecological integrity.This study assessed the water quality of Sumber Suko Spring in East Java,Indonesia,through an integrated ecological approach combining physicochemical,microbiological,biological,and hydrological parameters across wet and dry seasons.Physicochemical results showed stable temperature(24.1–26.7°C),near-neutral pH(6.4–6.9),and adequate dissolved oxygen(6.2–7.4 mg/L).However,nitrate concentrations were elevated(39.37–48.16 mg/L),exceeding natural background levels and indicating agricultural leaching,while phosphate values ranged between 0.12–0.21 mg/L.Microbial analysis revealed high total coliform counts(24 CFU/100mL),far above WHO standards,although E.coli was not detected.Plankton analysis identified 10 genera,with Microcystis aeruginosa dominating,particularly in the dry season,signaling risks of eutrophication.Shannon-Wiener diversity indices(H’)ranged from 1.25 to 1.67,with evenness values between 0.43 and 0.56,reflecting low-to-moderate community stability.Hydrological measurements showed seasonal discharge fluctuations from 14.6 L/s in the wet season to 7.8 L/s in the dry season,strongly correlated with rainfall.Overall,the integration of nutrient enrichment,coliform contamination,and cyanobacterial dominance indicates that Sumber Suko Spring is under ecological stress and does not meet drinking water standards without treatment.The findings highlight the urgent need for source protection,disinfection,and continuous monitoring within a water safety plan framework.This study provides evidence-based insights to support local policy alignment with WHO guidelines and emphasizes the importance of community participation in sustaining spring ecosystems for long-term water security.
基金supported by the National Natural Science Foundation of China(Nos.T222100,22205258,52302485 and 2024JJ5404).
文摘The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the electrodes and the propellant. The effects of spring pressure on the ignition and combustion of propellants have not yet been studied. In this paper, a universal testing machine and an electrochemical workstation were firstly utilized to investigate the compressive mechanical property and conductivity of Hydroxylamine Nitrate(HAN)-ECSP. The maximum pressure at which the propellant undergoes elastic deformation is 65 kPa. When the spring pressure increased from 5.1 k Pa to 20.4 kPa, the propellant resistance decreased from 56.8 Ω to 36.8 Ω.Various observation methods were employed to study the process of electrical energy injection and the ignition and combustion characteristics under constant voltage. Appropriately increasing the spring pressure can accelerate the injection of electrical energy into the propellant, increase the electrification current, and thus reduce the initial ignition delay time of the propellant. When the spring pressure is 20.4 kPa, the squeezing speed of the propellant is too fast, making it difficult for the propellant to be adequately heated at the electrode interface, which is unfavorable for ignition. Excessive spring pressure also leads to the accumulation of a large amount of combustion residue on the electrode plate, hindering the mixing and diffusion of hot gases during the second ignition process, preventing the gaseous flame of the propellant. When the spring pressure is 5.1 kPa, improving the working voltage can enhance the repeated ignition characteristics of the propellant.
文摘Self-Centering Piston-Based Braced Frames(SC-PBBFs)are designed to curtail structural damage under severe ground motions.The self-centering mechanism in this bracing mitigates structural damage during an earthquake,thereby reducing post-earthquake repair costs and contributing to seismic resilience.However,non-structural components,particularly those sensitive to floor acceleration,remain vulnerable,resulting in prolonged func-tional recovery times.This paper aims to address this limitation by introducing a novel structural archetype,the Self-Centering Viscous-Based Braced Frame(SC-VBBF),which integrates superelastic shape memory alloy(SMA)bars,viscous dampers(VDs),and friction springs(FSs).A streamlined analytical approach relies on the strength decoupling of VD from other components using aλfactor to design SC-VBBFs.To evaluate the effectiveness of the hybrid brace,a set of 4-,8-,and 12-story archetypes equipped with SC-PBBs and SC-VBBFs are simulated in OpenSees and analyzed under various earthquake types,including crustal,subcrustal,and subduction events.The results demonstrate the superior performance of the SC-VBBF withλ≤0.5 system compared to SC-PBBFs in mitigating floor accelerations under design-level earthquakes and improving seismic resilience.
基金National Natural Science Foundation of China (50675010)
文摘The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and forming time on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method （FEM） analysis.
基金Item Sponsored by Scientific and Technological Research Council of Turkey(107 M596)
文摘In recent years, the use of advanced high strength steels in automotive industry has been increased remarkably. Among advanced high strength steels, dual phase （DP） steels have gained a great attention owing to a combination of high strength and good formability. However, high strength usually increases the spring-back behavior of the material, which creates problems for the parts during the assembly. Thus, the uniaxial tensile deformation and spring-back behaviors of DP600 advanced high strength steel were investigated in rolling （0°）, diagonal （45°） , and transverse （90°） directions in the temperature range from room temperature （RT） to 300 ℃. All tests were performed at a deformation speed of 25 mm/min. A V-shaped die （60°） was used for the spring-back measurements. The results indicated that the formability and spring-back of the material were decreased with increasing the temperatures. The material showed complex behaviors in different directions and at different temperatures.
文摘The spring-back of a bending metal tube was studied through extensive experiments and finite element method （FEM） analysis. An approximate equation for the spring-back angle of bending was deduced. It is noted that the mechanical properties of the material （in a tubular form） are quite different from those found in the standard tensile tests （when the materials are in bar forms）. This is one of the major reasons that result in the discrepancies in the outcomes of experimental study, FEM calculations, and spring-back analysis. It is therefore of crucial importance to study the mechanical properties of the materials in their tubular forms. The experiments and FEM simulations prove that the spring-back angle is significantly affected by the mechanical properties of the materials. The angle decreases accordingly with plastic modulus, but changes inversely with the hardening index and elastic modulus The spring-back angle is also affected by the conditions of tube deformation： it increases accordingly with the relative bending radius but changes inversely with the relative wall thickness. In addition, the spring-back angle increases nonlinearly with the bending angle.
