Analysis on dynamic precision degradation mechanism of high-speed precision press

In order to investigate the impact factors and their affection on high-speed precision multilink punch press (MPP), the dynamic model with different joint clearance was established, and the influence of different clearance and speed on the dynamic positional repeatability of bottom dead center (BDC) was analyzed. The elastic dynamic model of high-speed MPP was established, the affection of the elastic deformation and elastic wave on the positional repeatability of the BDC were presented by using modal superposition method to solve dynamic equation. Meanwhile, experiments on the dynamic repeatability of the BDC of the punch during working were completed. At last, the comparison of the experimental results with the analyzed results was given, and based on which, it can be concluded that the clearance, elastic wave and deformation are the key factors of the dynamic repeatability precision of the BDC.

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A Novel Evaluation Method on the Precision of Linear Motor Feed System in High-Speed Machine Tools

Materials Science Forum ◽

10.4028/www.scientific.net/msf.836-837.220 ◽

2016 ◽

Vol 836-837 ◽

pp. 220-227 ◽

Cited By ~ 3

Author(s):

Xiao Jun Yang ◽

Yan Li ◽

Cheng Fang Ma ◽

Dun Lv ◽

Jun Zhang ◽

...

Keyword(s):

Mechanical System ◽

Machine Tools ◽

High Speed ◽

Evaluation Method ◽

Linear Motor ◽

Feed System ◽

Dynamic Precision ◽

Transmission Structure ◽

Accuracy And Repeatability ◽

High Speed Machine

The linear motor feed system can realize high-precision motion with high-speed and high-acceleration, which has a broad application in high-speed machine tools. In its unique zero transmission structure, the motor is connected directly with the mechanical system. The thrust harmonics and other disturbances act on the motor mover directly, which makes the tracking fluctuation more prominent. The traditional accuracy and repeatability of positioning cannot reflect the precision of the linear motor feed system in the process of high-speed movement. In this paper, a novel precision evaluation method which takes the dynamic precision as the index is proposed for the linear motor feed system in high-speed machine tools. The performance and precision of linear motor feed system are evaluated by the transient error, steady-state follow error and tracking fluctuation, respectively. Then the servo control model is established oriented to dynamic precision. The influences of NC instructions, servo system and mechanical system on the dynamic precision are discussed. It can be obtained that this new evaluation method on the precision can evaluate systematically the performance of the linear motor feed system in high-speed machine tools. Meanwhile it can reveal efficiently main factors which lead to the decline of dynamic precision and propose effective improvement methods.

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Congestion Control Call Admission Control (CC-CAC) Algorithm for Mobile Broadband Networks

European Journal of Electrical Engineering and Computer Science ◽

10.24018/ejece.2019.3.5.113 ◽

2019 ◽

Vol 3 (5) ◽

Author(s):

Ibrahim Saidu ◽

Abubakar Roko ◽

Nasir Aliyu Shinkafi ◽

Solomon Yese

Keyword(s):

Congestion Control ◽

Admission Control ◽

High Speed ◽

Call Admission Control ◽

Blocking Probability ◽

Degradation Mechanism ◽

Base Station ◽

Broadband Networks ◽

Mobile Broadband ◽

Call Admission

Mobile broadband networks are continuously faced with the challenge of limited resources due to the increasing demand for high speed Internet services. To manage these resources, call admission control (CAC) which determines whether or not a connection request should be accepted or rejected is one of the resource management techniques usually deployed. A Dynamic QoS-aware CAC algorithm was recently proposed to improve resource utilization. However, the algorithm detects congestion of the network only after it has occurred, which leads to increase in blocking probability and thus lead to reduction in throughput. In this paper, a congestion control call admission control (CC-CAC) algorithm is proposed to reduce call blocking and increase throughput of all connection classes. The CC-CAC employs a congestion control mechanism that regulates the base station buffer to operate at a target threshold. It also employs a dynamic bandwidth degradation mechanism to degrade the resources of the admitted connections when resources are not sufficient to admit more connections. The algorithm is evaluated using simulation. The results show that the proposed scheme outperforms the benchmark scheme in terms of decrease in blocking probability and increase in throughput for all connection classes.

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Analysis of Hot Spots Evolution on Brake Disc Using High-Speed Infrared Camera

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.417-418.317 ◽

2009 ◽

Vol 417-418 ◽

pp. 317-320 ◽

Cited By ~ 1

Author(s):

Jeong Guk Kim ◽

Sung Tae Kwon ◽

Sung Cheol Yoon

Keyword(s):

Hot Spots ◽

High Speed ◽

Hot Spot ◽

Degradation Mechanism ◽

Low Frequency ◽

Infrared Camera ◽

Material Design ◽

Brake Disc ◽

Ir Camera ◽

Thermal Phenomenon

The hot spot generation has been considered as the main degradation mechanism in railway brake disc. Therefore, the understanding of hot spots, also called hot judder, which is undesirable low frequency vibrations developed by non-uniform contact area between brake pad material and brake disc, is important for a better understanding of material design as well as enhancement of materials properties in railway brake disc. Also, infrared (IR) thermography is a powerful NDE technique for the characterization of thermal phenomenon in engineering components and/or systems including engineering materials. The high-speed IR camera provides the measurement of temperature change during brake operation as well as the images of temperature contour on the brake disc surface. In this investigation, damage evolution due to generation of hot spots on railway brake disc was investigated using the infrared thermography method. Moreover, based on obtained thermographic images of hot spots, the hot spots and thermal damage of railway brake disc during braking operation were qualitatively analyzed.

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Experimental Design about Degradation Mechanism of CAM and Preliminary Experiment Results

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.663.703 ◽

2013 ◽

Vol 663 ◽

pp. 703-707

Author(s):

Jian Zeng Li ◽

Jin Feng Wang ◽

Jian Ping Lin

Keyword(s):

Mechanical Property ◽

High Speed ◽

Degradation Mechanism ◽

Fatigue Property ◽

Peak Stress ◽

Confining Pressure ◽

Degradation Model ◽

Increase With Increase ◽

Cement Asphalt Mortar ◽

Confining Pressures

Cement Asphalt Mortar (CAM) layer is the key to the structure of slab track in the high-speed railways. In the running of high-speed railways, the CAM layer must bear the action of temperature change, initial defects and trains loading, it will lead to the degradation of CAM. This paper designed the experiments to study its mechanical property under confining pressure or water erosion, tensile property, fatigue property, interface stress of CAM and concrete roadbed; it will help us to establish the failure criterion and degradation model of CAM layer. Preliminary experiment chose three confining pressures to study the mechanical property of CAM; the results indicate that peak stress and ductility of CAM greatly increase with increase of confining pressure.

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Research status and development trend of ceramifiable silicone rubber composites: a brief review

Materials Research Express ◽

10.1088/2053-1591/ac4625 ◽

2021 ◽

Author(s):

Jianhua Li

Keyword(s):

Mechanical Properties ◽

Silicone Rubber ◽

High Speed ◽

High Performance ◽

Degradation Mechanism ◽

Research Work ◽

Development Trend ◽

High Tech ◽

Reaction Products ◽

Rubber Composites

Abstract Ceramifiable silicone rubber composites (CSR) are one of the most important industrially produced elastic technical materials. At present, there is a strong demand for CSR in the high-tech fields of high-speed rail, nuclear power, rocket and aerospace, which are still to be met. Many scholars have committed to the research work of improving the thermal stability, flame retardant, mechanical properties by changing the silicone rubber (SR) matrixes and filler, tremendous advances in CSR have been made for over the last decades where CSR intended for the high technology fields has evolved through different generations. In summary, the first-generation research is based on matrix reaction, the second-generation research is on reaction products, and the third-generation research is on fillers effects. In this review, the evolution of CSR and the synthesis routes, reaction mechanism, and degradation mechanism are introduced and analysed; fillers, various types of CSR based composites as well as the flame retardancy and mechanical properties are reviewed. Finally, the problems of developing high-performance CSRs are proposed and discussed. This review provides a theoretical basis and supporting data for the application of high-performance CSR, as well as provides details on the fire prevention mechanism of CSR.

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Analysis on dynamic precision reliability of high-speed precision press based on Monte Carlo method

Nonlinear Dynamics ◽

10.1007/s11071-017-3857-7 ◽

2017 ◽

Vol 90 (4) ◽

pp. 2979-2988 ◽

Cited By ~ 6

Author(s):

Maohua Xiao ◽

Guosheng Geng ◽

Guohong Li ◽

Hao Li ◽

Runnan Ma

Keyword(s):

Monte Carlo ◽

Monte Carlo Method ◽

High Speed ◽

Dynamic Precision

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Failure Analysis Using Optical Evaluation Technique (OBIC) of LDs for Fiber Optical Communication

MRS Proceedings ◽

10.1557/proc-1195-b01-02 ◽

2009 ◽

Vol 1195 ◽

Cited By ~ 2

Author(s):

Tatsuya Takeshita ◽

Hiromi Oohashi

Keyword(s):

High Power ◽

High Speed ◽

High Performance ◽

Degradation Mechanism ◽

Nonradiative Recombination ◽

Optical Source ◽

Thermo Electric ◽

Incident Wavelength ◽

Erbium Doped Fiber Amplifier ◽

Before And After

AbstractThe introduction of high-speed services for fiber-optic access subscribers has led to a huge growth in data traffic. The rapid diversification of services means that next generation networks must be built quickly, economically and reliably.A high temperature laser allows us to eliminate the thermo-electric cooler conventionally needed in a transmitter module, which results in reductions in cost, power consumption and size. Moreover, a high-power laser provides a wide tolerance when coupling optical fibers. In addition, a high-power pump laser is needed to realize a wide-band and high-power erbium-doped fiber amplifier. This makes high-performance laser chips one of the keys to achieving highly reliable and cost-effective systems.In terms of laser reliability, we must clarify the degradation mechanism and postpone or suppress degradation if we are to achieve a reliable high-performance laser. We have analyzed degraded lasers using the optical beam induced current (OBIC) technique. When there are nonradiative recombination centers in the degraded region, the OBIC intensity decreases with increases in recombination density. This technique has the advantages of being non-destructive and highly sensitive. In addition, it provides high space resolution in degradation analyses.The OBIC is measured through the window of a transistor outline (TO) can before and after aging. Then, by using the same LDs we can detect an OBIC change for several aging times. We can both detect the degraded region and layer, and estimate the degree of laser degradation by employing the relative OBIC intensity prior to aging. This OBIC technique is useful for analyzing the degree of laser degradation.Moreover, the incident wavelength can be changed by changing the optical source in the OBIC measurement setup, which in turn changes the absorption layer and the penetration distance. Some degraded laser layers are reveled by using these several wavelengths absorbed in different layers. In addition, degradation in the waveguide interior is detected by using an incident wavelength with long penetration. Thus, by monitoring the OBIC intensity at several wavelengths as well as before and after aging, we are able to discuss sudden and wear-out laser failures. In our presentation, we will introduce examples using the OBIC technique that contributed to the improvement of laser reliability.

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Infrared Thermographic Analysis of Railway Brake Disc during Braking

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.488-489.597 ◽

2011 ◽

Vol 488-489 ◽

pp. 597-600 ◽

Cited By ~ 2

Author(s):

Jeong Guk Kim ◽

Sung Tae Kwon ◽

Sung Cheol Yoon ◽

Byeong Choon Goo

Keyword(s):

Hot Spots ◽

High Speed ◽

Hot Spot ◽

Degradation Mechanism ◽

Infrared Camera ◽

Brake Disc ◽

Ir Camera ◽

Train Speed ◽

Thermographic Analysis ◽

Temperature Contour

The temperature monitoring on the surface of the railway brake disc was performed using high-speed infrared (IR) camera. The railway brake disc was developed for disc braking of maximum train speed of 180 km/h. The braking tests were conducted with a full scale dynamometer, and a high-speed infrared camera was employed to monitor temperature evolution on the brake disc during braking operation. The high-speed IR camera provides the measurement of temperature change during braking as well as the images of temperature contour on the brake disc surface. In general, the hot spot generation has been considered the main degradation mechanism in railway brake disc. In this investigation, damage evolution due to generation of hot spots on railway brake disc was investigated using the infrared thermography method.

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