Machine Hammer Peening(MHP)is an emergent treatment that induces high compressive Residual Stresses(RS)which can enhance the in-service performance of components.This paper studies the use of small diameter MHP tools ...Machine Hammer Peening(MHP)is an emergent treatment that induces high compressive Residual Stresses(RS)which can enhance the in-service performance of components.This paper studies the use of small diameter MHP tools to improve the Surface Integrity(SI)of the nickel-based alloy Inconel 718 used in critical aero-engine components.Complementarily,the relaxation of RS is analyzed by in-situ annealing tests at in-service temperature combined with X-ray diffraction measurement.For this purpose,age hardened Inconel 718 discs were turned as reference condition,and then a pneumatic MHP tool was used under different conditions:two tool diameters(4 mm and 12 mm),feed rates(2.5 m/min and 5.0 m/min)and stepover distances(0.07 mm and 0.35 mm).Subsequently,surface topography characterization,RS measurements,nanoindentation tests,and microstructural observations were conducted.The in-situ annealing tests were done in the X-ray diffractometer at 550°C for exposure periods from 0 to 20 h.The results demonstrate that 4 mm diameter tools generate smooth surfaces and induce significant compressive RS within a0.5 mm thick layer.Residual stresses are relaxed,but they remain compressive even after a long thermal exposure.The microstructure of the surface layer(<10–15μm)was affected by the preceding turning operation,but importantly,MHP did not induce additional damage.展开更多
Pneumatic down-the-hole hammer, serving as rock-breaking tool, possesses appeal for directional drilling due to its high rate of penetration. However, corresponding experimental studies on existing hammers for directi...Pneumatic down-the-hole hammer, serving as rock-breaking tool, possesses appeal for directional drilling due to its high rate of penetration. However, corresponding experimental studies on existing hammers for directional drilling have rarely been reported, and a model for evaluating their output performance is absent. This study proposes a novel structure of self-rotating pneumatic hammer(NSH)with a built-in rotational mechanism, which converts partial impact energy of the piston to rotate the drill bit and, consequently, enables dual functions of impact and rotate drill bit. The energy is converted via a screw key-groove mechanism, and the wedge-shaped teeth mechanism ensures that the drill bit rotates clockwise during the piston moves downward. The computational fluid dynamics method is applied to simulate the dynamic response of airflow and piston during the operation of Φ127NSH.Meanwhile, a test bench is established to record data concerning chamber pressure and piston displacement, as well as recording its operational status and rock fragmentation during drilling into granite. The results showed that the maximum error between simulated and experimental data is 8.2%.The Φ127NSH successfully achieves dual impact and rotary drilling functions, and granite smoothly feeds and forms a continuous shear rock zone. In addition, the effects of torque load, engagement distance in rotation sleeves, and well deviation angle towards the performance of NSH were studied in detail. The designed Φ127NSH operates at an impact velocity of 3.98 m/s, impact frequency of 12.55 Hz, and rotational speed of 29.51 r/min under a mass-flow rate of 0.18 kg/s, torque load of 400 N·m, engagement distance of 40 mm, and well deviation angle of 0°. The torque load adversely affects the NSH output performance. Increasing the engagement distance improves impact performance while reducing rotational performance. The performance variation of the NSH is minimal when drilling directional wells with varying deviation angles.展开更多
The differences in damage values,residual stresses,microstructure and mechanical properties of Ti–6Al–4V alloy under hammer forging and press forging were explored through physical experiments and numerical simulati...The differences in damage values,residual stresses,microstructure and mechanical properties of Ti–6Al–4V alloy under hammer forging and press forging were explored through physical experiments and numerical simulations.The results showed that the temperature field and equivalent strain field of forgings under the hammer forging process were more uniformly distributed,resulting in smaller surface cracks and better residual stress distribution.The impact dynamic loading of hammer forging leads to forgings with higher dislocation densities,while the stabilized strain rate of press forging results in forgings exhibiting finer grain sizes.In this context,the yield strength enhancement of forgings by both processes was nearly identical,while the forgings demonstrated more excellent elongation under the hammer forging process.Additionally,increasing the number of blows in the hammer forging process or enhancing the loading rate in the press forging process can optimize the residual stress distribution of the forgings while simultaneously promoting dislocation multiplication and grain refinement.展开更多
With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure m...With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure modes are transformed.In order to reveal the failure mode and transformation rule of reinforced concrete slabs under impact loads,a dynamic impact response test was carried out using a drop hammer test device.The dynamic data pertaining to the impact force,support reaction force,structural displacement,and reinforcement strain were obtained through the use of digital image correlation technology(DIC),impact force measurement,and strain measurement.The analysis of the ultimate damage state of the reinforced concrete slab identified four distinct types of impact failure modes:local failure by stamping,overall failure by stamping,local-overall coupling failure,and local failure by punching.Additionally,the influence laws of hammerhead shape,hammer height,and reinforcement ratio on the dynamic response and failure mode transformation of the slab were revealed.The results indicate that:(1)The local damage to the slab by the plane hammer is readily apparent,while the overall damage by the spherical hammer is more pronounced.(2)In comparison to the high reinforcement ratio slabs,the overall bending resistance of the low reinforcement ratio slabs is significantly inferior,and the slab back exhibits further cracks.(3)As the hammer height increases,the slab failure mode undergoes a transformation,shifting from local failure by stamping and overall failure by stamping to local-overall coupling failure and local failure by punching.(4)Three failure mode thresholds have been established,and by comparing the peak impact force with the failure thresholds,the failure mode of the slab can be effectively determined.展开更多
The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed. By means of the balance chart of energy, the method and formulas to calculate every level efficiency and the ...The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed. By means of the balance chart of energy, the method and formulas to calculate every level efficiency and the total efficiency of steam drived hammer are formed.With the aid of actual data of plants,the actual efficiency of steam drived hammer is got. The working principle and the driving system of electro-hydraulic hammer are introduced. The procedure of energy energy of this hammer is analyzed. The utilization ratio of energy of this type of hammer is got. It is shown that the efficiency of electro-hydraulic hammer is 7 times as much as that of steam drived hammer.展开更多
The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a...The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a fare precision in the predictions. By using the model of solid liquid two phase flow, the gas storage tank, pressure relief valves and slow closure reverse control valves were compared with practical engineering problems, and the functions of gas storage tank in attenuating water hammer pressure were further investigated. [展开更多
[Objectives]To better design and test 9FQM1000 branch and straw hammer mill in view of the problems of large output,low utilization rate,traditional incineration and easily polluting environment of the new agricultura...[Objectives]To better design and test 9FQM1000 branch and straw hammer mill in view of the problems of large output,low utilization rate,traditional incineration and easily polluting environment of the new agricultural economic organization's straw and waste branches.[Methods]This hammer mill adopts dual-channel feeding method.It adopts the basic working principle of disc shredding and hammer crushing.Besides,it makes design of the structure and driving system of the branch and straw hammer mill.9FQM1000 type branch and straw hammer mill can finely crush the branches and straws.Finally,it makes a trial production of 9FQM1000 type branch and straw hammer mill.[Results]The prototype test showed that the combined crushing structure of 9FQM1000 type branch and straw hammer mill is reliable,and the production capacity is 3000 kg/h.[Conclusions]The automatic feeder makes the crushing operation more stable,the labor intensity is reduced,the structure is simple,and it can be moved by traction.It is environmentally friendly and pollution-free.It has the characteristics of high safety,automation and high production efficiency.Also,crushed materials can be used as edible fungus culture medium,animal feed,organic fertilizer,etc.,and can be further compressed into biomass fuel,and the crushed branches can also be returned to the field.展开更多
A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience ...A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience and experiments,for the matching relationships of inner pressure is complex and the impact performance is influenced by many factors.In this paper,the operating principle of a YDC type hydraulic hammer was investigated,the force applied to the main moving components(valve core and hammer)was analyzed and a dynamic model of valve core and hammer in each operating stage was established.Then,a hydraulic hammer performance optimization design software was developed on the Matlab software platform,and the performance parameters calculated by the software were compared with the laboratory test results.The following research results were obtained.Firstly,single impact energy,impact frequency and impact power increase with the increase of pump displacement or the decrease of flow bean diameter,and they increase firstly and then decrease with the increase of area difference between the upper and lower chambers.Secondly,with the increase of hammer weight,single impact energy and impact power increase,but the impact frequency decreases slowly.Thirdly,with the increase of hammer travel,single impact energy presents an increasing trend,impact frequency presents a decreasing trend and impact power basically remains unchanged.Fourthly,with the increase of valve core weight,single impact energy presents an increasing trend,while both impact frequency and impact power decrease.Fifthly,the parameter combination corresponding to the optimal single impact energy and impact power is A5B1C5D4E3F2,and the effect of displacement on single impact energy and impact power is the greatest.It is concluded that under the existing displacement and pressure of drilling pumps,the impact performance of the hydraulic hammer can be increased effectively by improving the structure of the hydraulic hammer and thus increasing its work displacement.展开更多
The process of DTH（down-the-hole） hammer drilling has been characterized as a very complex phenomenon due to its high nonlinearity,large deformation and damage behaviors.Taking brittle materials（concrete,granite an...The process of DTH（down-the-hole） hammer drilling has been characterized as a very complex phenomenon due to its high nonlinearity,large deformation and damage behaviors.Taking brittle materials（concrete,granite and sandstone） as impact specimens,the explicit time integration nonlinear finite element code LS-DYNA was employed to analyze the impact process and the penetration boundary conditions of DTH hammer percussive drilling system.Compared with previous studies,the present model contains several new features.One is that the 3D effects of DTH hammer drilling system were considered.Another important feature is that it took the coupling effects of brittle materials into account to the bit-specimen boundary of the drilling system.This distinguishes it from the traditional approaches to the bit-rock intersection,in which nonlinear spring models are usually imposed.The impact forces,bit insert penetrations and force-penetration curves of concrete,granite and sandstone under DTH hammer impact have been recorded;the formation of craters and fractures has been also investigated.The impact loads of piston-bit interaction appear to be relatively sensitive to piston impact velocity.The impact between piston-bit interaction occurs at two times larger forces,whereas the duration of the first impact doesn＇t change with respect to the piston velocity.The material properties of impact specimen do not affect the first impact process between the piston and bit.However,the period between the two impacts and the magnitudes of the second impact forces greatly depend on the specimen material properties.It is found that the penetration depth of specimen is dependent on the impact force magnitude and the macro-mechanical properties of the brittle materials.展开更多
A new typed hydraulic system of electro hydraulic hammer is researched and developed By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed...A new typed hydraulic system of electro hydraulic hammer is researched and developed By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed The experimental research which is emphasized on the blowing stroke is also performed It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working Especially it possesses better dynamic characteristics展开更多
This paper presents an analytical investigation of water hammer in a hydraulic pressurized pipe system with a throttled surge chamber located at the junction between a tunnel and a penstock, and a valve positioned at ...This paper presents an analytical investigation of water hammer in a hydraulic pressurized pipe system with a throttled surge chamber located at the junction between a tunnel and a penstock, and a valve positioned at the downstream end of the penstock. Analytical formulas of maximum water hammer pressures at the downstream end of the tunnel and the valve were derived for a system subjected to linear and slow valve closure. The analytical results were then compared with numerical ones obtained using the method of characteristics. There is agreement between them. The formulas can be applied to estimating water hammer pressure at the valve and transmission of water hammer pressure through the surge chamber at the junction for a hydraulic pipe system with a surge chamber.展开更多
基金the financial support given by EPSRC to the Grant LOFAMO(No.EP/X023281/1)the Basque Government for the financial support given from Elkartek Program to the Project FRONTIERS 2022—Superficies Multifuncionales en la Frontera del Conocimiento(No.KK2022/00109)。
文摘Machine Hammer Peening(MHP)is an emergent treatment that induces high compressive Residual Stresses(RS)which can enhance the in-service performance of components.This paper studies the use of small diameter MHP tools to improve the Surface Integrity(SI)of the nickel-based alloy Inconel 718 used in critical aero-engine components.Complementarily,the relaxation of RS is analyzed by in-situ annealing tests at in-service temperature combined with X-ray diffraction measurement.For this purpose,age hardened Inconel 718 discs were turned as reference condition,and then a pneumatic MHP tool was used under different conditions:two tool diameters(4 mm and 12 mm),feed rates(2.5 m/min and 5.0 m/min)and stepover distances(0.07 mm and 0.35 mm).Subsequently,surface topography characterization,RS measurements,nanoindentation tests,and microstructural observations were conducted.The in-situ annealing tests were done in the X-ray diffractometer at 550°C for exposure periods from 0 to 20 h.The results demonstrate that 4 mm diameter tools generate smooth surfaces and induce significant compressive RS within a0.5 mm thick layer.Residual stresses are relaxed,but they remain compressive even after a long thermal exposure.The microstructure of the surface layer(<10–15μm)was affected by the preceding turning operation,but importantly,MHP did not induce additional damage.
基金supported by the Natural Science Foundation of Jilin Province(YDZJ202101ZYTS143).
文摘Pneumatic down-the-hole hammer, serving as rock-breaking tool, possesses appeal for directional drilling due to its high rate of penetration. However, corresponding experimental studies on existing hammers for directional drilling have rarely been reported, and a model for evaluating their output performance is absent. This study proposes a novel structure of self-rotating pneumatic hammer(NSH)with a built-in rotational mechanism, which converts partial impact energy of the piston to rotate the drill bit and, consequently, enables dual functions of impact and rotate drill bit. The energy is converted via a screw key-groove mechanism, and the wedge-shaped teeth mechanism ensures that the drill bit rotates clockwise during the piston moves downward. The computational fluid dynamics method is applied to simulate the dynamic response of airflow and piston during the operation of Φ127NSH.Meanwhile, a test bench is established to record data concerning chamber pressure and piston displacement, as well as recording its operational status and rock fragmentation during drilling into granite. The results showed that the maximum error between simulated and experimental data is 8.2%.The Φ127NSH successfully achieves dual impact and rotary drilling functions, and granite smoothly feeds and forms a continuous shear rock zone. In addition, the effects of torque load, engagement distance in rotation sleeves, and well deviation angle towards the performance of NSH were studied in detail. The designed Φ127NSH operates at an impact velocity of 3.98 m/s, impact frequency of 12.55 Hz, and rotational speed of 29.51 r/min under a mass-flow rate of 0.18 kg/s, torque load of 400 N·m, engagement distance of 40 mm, and well deviation angle of 0°. The torque load adversely affects the NSH output performance. Increasing the engagement distance improves impact performance while reducing rotational performance. The performance variation of the NSH is minimal when drilling directional wells with varying deviation angles.
基金supported by the National Natural Science Foundation of China(Nos.52175145 and 51775427)the Key Research and Development Projects of Shaanxi Province(Grant No.2023-YBGY-335).
文摘The differences in damage values,residual stresses,microstructure and mechanical properties of Ti–6Al–4V alloy under hammer forging and press forging were explored through physical experiments and numerical simulations.The results showed that the temperature field and equivalent strain field of forgings under the hammer forging process were more uniformly distributed,resulting in smaller surface cracks and better residual stress distribution.The impact dynamic loading of hammer forging leads to forgings with higher dislocation densities,while the stabilized strain rate of press forging results in forgings exhibiting finer grain sizes.In this context,the yield strength enhancement of forgings by both processes was nearly identical,while the forgings demonstrated more excellent elongation under the hammer forging process.Additionally,increasing the number of blows in the hammer forging process or enhancing the loading rate in the press forging process can optimize the residual stress distribution of the forgings while simultaneously promoting dislocation multiplication and grain refinement.
基金Supported by the National Natural Science Foundation of China(Grant No.52078283)Shandong Provincial Natural Science Foundation(Project No.ZR2024MA094)。
文摘With the change of the main influencing factors such as structural configuration and impact conditions,reinforced concrete slabs exhibit different mechanical behaviors with different failure patterns,and the failure modes are transformed.In order to reveal the failure mode and transformation rule of reinforced concrete slabs under impact loads,a dynamic impact response test was carried out using a drop hammer test device.The dynamic data pertaining to the impact force,support reaction force,structural displacement,and reinforcement strain were obtained through the use of digital image correlation technology(DIC),impact force measurement,and strain measurement.The analysis of the ultimate damage state of the reinforced concrete slab identified four distinct types of impact failure modes:local failure by stamping,overall failure by stamping,local-overall coupling failure,and local failure by punching.Additionally,the influence laws of hammerhead shape,hammer height,and reinforcement ratio on the dynamic response and failure mode transformation of the slab were revealed.The results indicate that:(1)The local damage to the slab by the plane hammer is readily apparent,while the overall damage by the spherical hammer is more pronounced.(2)In comparison to the high reinforcement ratio slabs,the overall bending resistance of the low reinforcement ratio slabs is significantly inferior,and the slab back exhibits further cracks.(3)As the hammer height increases,the slab failure mode undergoes a transformation,shifting from local failure by stamping and overall failure by stamping to local-overall coupling failure and local failure by punching.(4)Three failure mode thresholds have been established,and by comparing the peak impact force with the failure thresholds,the failure mode of the slab can be effectively determined.
文摘The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed. By means of the balance chart of energy, the method and formulas to calculate every level efficiency and the total efficiency of steam drived hammer are formed.With the aid of actual data of plants,the actual efficiency of steam drived hammer is got. The working principle and the driving system of electro-hydraulic hammer are introduced. The procedure of energy energy of this hammer is analyzed. The utilization ratio of energy of this type of hammer is got. It is shown that the efficiency of electro-hydraulic hammer is 7 times as much as that of steam drived hammer.
文摘The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a fare precision in the predictions. By using the model of solid liquid two phase flow, the gas storage tank, pressure relief valves and slow closure reverse control valves were compared with practical engineering problems, and the functions of gas storage tank in attenuating water hammer pressure were further investigated. [
基金Project of Natural Science Foundation of Shandong Province(ZR2018PEE015)Special Funding Project of Shandong Provincial Scientific Research Institutions(Lu Cai Jiao Zhi[2016]No.65).
文摘[Objectives]To better design and test 9FQM1000 branch and straw hammer mill in view of the problems of large output,low utilization rate,traditional incineration and easily polluting environment of the new agricultural economic organization's straw and waste branches.[Methods]This hammer mill adopts dual-channel feeding method.It adopts the basic working principle of disc shredding and hammer crushing.Besides,it makes design of the structure and driving system of the branch and straw hammer mill.9FQM1000 type branch and straw hammer mill can finely crush the branches and straws.Finally,it makes a trial production of 9FQM1000 type branch and straw hammer mill.[Results]The prototype test showed that the combined crushing structure of 9FQM1000 type branch and straw hammer mill is reliable,and the production capacity is 3000 kg/h.[Conclusions]The automatic feeder makes the crushing operation more stable,the labor intensity is reduced,the structure is simple,and it can be moved by traction.It is environmentally friendly and pollution-free.It has the characteristics of high safety,automation and high production efficiency.Also,crushed materials can be used as edible fungus culture medium,animal feed,organic fertilizer,etc.,and can be further compressed into biomass fuel,and the crushed branches can also be returned to the field.
基金supported by CNPC Scientific Research and Technology Development Project“Study on New Drilling Techniques and Methods”(No.2014A-4211).
文摘A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience and experiments,for the matching relationships of inner pressure is complex and the impact performance is influenced by many factors.In this paper,the operating principle of a YDC type hydraulic hammer was investigated,the force applied to the main moving components(valve core and hammer)was analyzed and a dynamic model of valve core and hammer in each operating stage was established.Then,a hydraulic hammer performance optimization design software was developed on the Matlab software platform,and the performance parameters calculated by the software were compared with the laboratory test results.The following research results were obtained.Firstly,single impact energy,impact frequency and impact power increase with the increase of pump displacement or the decrease of flow bean diameter,and they increase firstly and then decrease with the increase of area difference between the upper and lower chambers.Secondly,with the increase of hammer weight,single impact energy and impact power increase,but the impact frequency decreases slowly.Thirdly,with the increase of hammer travel,single impact energy presents an increasing trend,impact frequency presents a decreasing trend and impact power basically remains unchanged.Fourthly,with the increase of valve core weight,single impact energy presents an increasing trend,while both impact frequency and impact power decrease.Fifthly,the parameter combination corresponding to the optimal single impact energy and impact power is A5B1C5D4E3F2,and the effect of displacement on single impact energy and impact power is the greatest.It is concluded that under the existing displacement and pressure of drilling pumps,the impact performance of the hydraulic hammer can be increased effectively by improving the structure of the hydraulic hammer and thus increasing its work displacement.
基金supported by the National Natural Science Foundation of China (No. 50475056)
文摘The process of DTH（down-the-hole） hammer drilling has been characterized as a very complex phenomenon due to its high nonlinearity,large deformation and damage behaviors.Taking brittle materials（concrete,granite and sandstone） as impact specimens,the explicit time integration nonlinear finite element code LS-DYNA was employed to analyze the impact process and the penetration boundary conditions of DTH hammer percussive drilling system.Compared with previous studies,the present model contains several new features.One is that the 3D effects of DTH hammer drilling system were considered.Another important feature is that it took the coupling effects of brittle materials into account to the bit-specimen boundary of the drilling system.This distinguishes it from the traditional approaches to the bit-rock intersection,in which nonlinear spring models are usually imposed.The impact forces,bit insert penetrations and force-penetration curves of concrete,granite and sandstone under DTH hammer impact have been recorded;the formation of craters and fractures has been also investigated.The impact loads of piston-bit interaction appear to be relatively sensitive to piston impact velocity.The impact between piston-bit interaction occurs at two times larger forces,whereas the duration of the first impact doesn＇t change with respect to the piston velocity.The material properties of impact specimen do not affect the first impact process between the piston and bit.However,the period between the two impacts and the magnitudes of the second impact forces greatly depend on the specimen material properties.It is found that the penetration depth of specimen is dependent on the impact force magnitude and the macro-mechanical properties of the brittle materials.
文摘A new typed hydraulic system of electro hydraulic hammer is researched and developed By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed The experimental research which is emphasized on the blowing stroke is also performed It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working Especially it possesses better dynamic characteristics
基金supported by the National Natural Science Foundation of China (Grant No.50539070)the Major State Basic Research Development Program of China (Grant No.2006CB403304)
文摘This paper presents an analytical investigation of water hammer in a hydraulic pressurized pipe system with a throttled surge chamber located at the junction between a tunnel and a penstock, and a valve positioned at the downstream end of the penstock. Analytical formulas of maximum water hammer pressures at the downstream end of the tunnel and the valve were derived for a system subjected to linear and slow valve closure. The analytical results were then compared with numerical ones obtained using the method of characteristics. There is agreement between them. The formulas can be applied to estimating water hammer pressure at the valve and transmission of water hammer pressure through the surge chamber at the junction for a hydraulic pipe system with a surge chamber.
