Tang Y.L.,China Special Equipment Inspection And Research Institute
Applied Mechanics and Materials | Year: 2013
In order to meet the needs of conveniently, fast and accurately calculating the balance coefficient in lift supervisory inspection, this paper proposed a novel method based on android smartphone terminal. First, the boundary value problem was discovered in the balance coefficient curve fitting, and the fusion algorithm of curve fitting and interpolation is proposed. Secondly, the coefficient calculation software was developed based on android smartphone after its function was designed. The experiments show that it can meet the requirements of test and the efficiency is also greatly improved. © (2013) Trans Tech Publications, Switzerland.
Chen G.,China Special Equipment Safety Supervision Administration |
Deng Y.,China Special Equipment Inspection And Research Institute
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2011
By increasing the yield strengths of austenitic stainless steels for pressure vessels with strain hardening techniques, the elastic load bearing capacity of austenitic stainless steel pressure vessels can be significantly improved. Two kinds of strain hardening methods are often used for austenitic stainless steel pressure vessels: Avesta model for ambient temperature applications and Ardeform model for cryogenic temperature applications. Both methods are obtained from conventional design rules based on the linear elastic theory, and only consider the hardening effect from materials. Consequently this limits the applications of strain hardening techniques for austenitic stainless steel pressure vessels because of safety concerns. This paper investigates the effect of strain hardening on the load bearing capacity of austenitic stainless steel pressure vessels under large deformation, based on the elastic-plastic theory. Firstly, to understand the effect of strain hardening on material behavior, the plastic instability loads of a round tensile bar specimen are derived under two different loading paths and validated by experiments. Secondly, to investigate the effect of strain hardening on pressure vessels strength, the plastic instability pressure under strain hardening is derived and further validated by finite element simulations. Further, the safety margin of pressure vessels after strain hardening is analyzed by comparing the safety factor values calculated from bursting tests, finite element analyses, and standards. The researching results show that the load bearing capacity of pressure vessels at ambient temperature is independent of the loading history when the effects of both material strain hardening and structural deformation are considered. Finite element simulations and bursting tests results show that the minimum safety factor of austenitic stainless steel pressure vessels with 5% strain hardening is close to the recommended value for common pressure vessels specified in the European pressure vessel standard. The proposed study also shows that in the strain hardening design of austenitic stainless steel pressure vessels, the calculation for plastic instability pressure could use theoretical formula or finite element analyses based on geometrical dimensions and material property parameters before strain hardening, but a 5% strain should be employed as a design limit. The proposed research can be used for the strain hardening design of austenitic stainless steel pressure vessels safely. © 2011 Chinese Journal of Mechanical Engineering.
Liu Y.,Tsinghua University |
Wang H.-K.,China Special Equipment Inspection And Research Institute |
Zhang X.,Tsinghua University
International Journal of Mechanics and Materials in Design | Year: 2013
The equation of state (EOS) plays an important role in high-velocity impact process since phase transformation, melting, and even vaporization may happen under such extreme loading conditions. It is desired to adopt an accurate EOS covering a large range of points in the phase space. This paper proposes a combined molecular dynamics and material point method approach to simulate the high-velocity impact process. The EOS data are first obtained from a series of molecular dynamics computations, and the parameters are fitted. Then the EOS parameters are adopted in the material point method simulation to model the impact process. Simulation results show that the fitted EOS can be very accurate compared to experimental results. The shape of the debris cloud obtained by our multiscale method agrees well with that of the experiments. An empirical equation is also proposed to predict the fraction of melting material in the high-velocity impact process. © 2013 Springer Science+Business Media Dordrecht.
Wang Z.D.,Beijing Jiaotong University |
Yao K.,Beijing Jiaotong University |
Deng B.,Beijing Jiaotong University |
Ding K.Q.,China Special Equipment Inspection And Research Institute
NDT and E International | Year: 2010
Compared to traditional nondestructive testing methods, the technique of metal magnetic memory (MMM) is a more effective way in evaluating early damages of ferromagnets due to the existence of material stresses. In practical engineering, this technique has been extensively applied in different fields. However, very limited quantitative research has been carried out on quantitatively studying the relations between the stress state and self-magnetic flux leakage (SMFL) signal. In this paper, the distribution of SMFL is investigated based on the theory of magnetic charges. A linear description of the magnetic charge and the stress state is given. The theory can capture some basic characteristics of the SMFL distribution in the stress concentration of ferromagnets, e.g. the tangential SMFL component HP(x) reaching a maximum value and the normal component HP(y) changing positive-negative sign in the maximum stress concentration zone (SCZ). Moreover, the effects of the stress-concentration range and lift-off value on SMFL signals are discussed as well. © 2010 Elsevier Ltd. All rights reserved.
Tang Y.L.,China Special Equipment Inspection And Research Institute
Applied Mechanics and Materials | Year: 2014
Speed tolerance between handrail and the steps, pallets or belt of the escalator or moving walk is important to the passengers' safety. This thesis proposes a novel design of ARM Cotex-M4 based double-channeled testing instrument for speed tolerance test which adopts two independent optical encoders to acquire the speed of handrail and the steps. The design handles parameter information obtained through two independent optical encoders by ARM Cotex-M4, then calculates and displays the result by LCD. The experiment shows that the measuring error and resolution ratio agree well with the standard. It can quickly detect the speed tolerance between handrail and the steps and the function of intelligent indication is convenient to the inspector. The field test shows that it can meet the requirements of test and the efficiency is also greatly improved. © (2014) Trans Tech Publications, Switzerland.
Duan Z.-X.,China Special Equipment Inspection And Research Institute
Gongcheng Lixue/Engineering Mechanics | Year: 2012
By the strain analysis and energy method, the expressions of the axial stress and circumferential stress of an elbow under the action of an in-plane bending moment are gained, and the high order stress solution for an elbow subjected to an in-plane bending moment is suggested. The high order stress solution for an elbow subjected to an in-plane bending moment is compared with the solution using the other methods. It is obtained from the comparison that the high order solution is more accurate and is suitable for elbows without the limit of λ. The high order stress solution is suitable for an elbow under an in-plane close-bending moment or an in-plane open-bending moment.
Lv X.,China Special Equipment Inspection And Research Institute
Proceedings - 2015 7th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2015 | Year: 2015
To get rid of the weaknesses of the traditional defect inspection of the bolts, such as low efficiency, high cost, and poor-feasibility, a novel inspection approach for bolt looseness inspection based on the image processing technology using the charge coupled device (CCD) as the image sensor and the support vector machine (SVM) was proposed. The digital image of the tested bolt was collected by a DS-2AE7162-A CCD digital camera and input into computer by an image acquisition device. The original digital image with noise was processed by Gaussian filter and histogram equation to reduce its noise, and located by YCbCr color space. The samples feature descriptions of the bolts were extracted. A linear classifier model for defect inspection which based on the SVM was proposed. Experiments on several datasets demonstrate our approach is characterized by low cost, high efficiency, and easy realized. © 2015 IEEE.
Liu C.J.,Key Laboratory of Safety Science of Pressurized System |
Chen Y.,China Special Equipment Inspection And Research Institute
Materials and Design | Year: 2011
Hydrogen reformer furnaces have been widely used in the petrochemical industry to produce the hydrogen-rich gas from a mixture of hydrocarbons and steam at high temperature. However, the degradation of material microstructure was frequently encountered in the tubes due to high temperature service, leading to their premature failure. The aim of this paper was to address the variations of the microstructure and mechanical properties of HP40Nb hydrogen reformer tubes after aging treatment and long-term service at temperature of 900 °C. The results showed that the grain boundaries became coarsening due to the precipitation of the chromium-rich carbides and the secondary carbides precipitated in the matrix after aging treatment and long-term service. The mechanical properties of the HP40Nb tube obviously degraded after short-term service and then almost kept unchanged. The interdendritic carbide content can be used as a key index for the life predication of the used tube since there was a linear relationship between the logarithm of carbide content and the logarithm of time. © 2010 Elsevier Ltd.
Cai Q.,China Special Equipment Inspection And Research Institute
Advances in Energy Science and Equipment Engineering - Proceedings of International Conference on Energy Equipment Science and Engineering, ICEESE 2015 | Year: 2015
In order to improve the performance of the injector, two-stage steam-water jet injector was proposed. The investigation of the injector was carried out experimentally, along with the parametric study that considered the effects of different operating parameters on the performance. The results show that there exists a maximum in the effect of inlet steam pressure on the discharge water pressure. The discharge water pressure firstly increases and then decreases with the increase of inlet water mass flux. The increase of inlet water temperature leads to the fast degradation of the injector performance. The results also show that experimental results are in good agreement with calculated values. The experimental data agree with the calculated predictions within ±15%. © 2015 Taylor & Francis Group, London.
Wu F.Q.,China Special Equipment Inspection And Research Institute
Applied Mechanics and Materials | Year: 2014
Based on the multi-body system dynamics in the ADAMS environment, a virtual prototype of the reel fulcrum of crane was developed. In this model, the whole system was disassembled lifting mechanism system with flexible body dynamics model of the wire rope. The virtual running environment was established according to the actual crane operation cases, which is designed the hanging & lifting working process. It is the key step to build the reel fulcrum dynamics model for performance analysis of system dynamics, which is the basis for the optimize design of the reel fulcrum of crane. Theoretical model analysis usually does not consider the coupling force status of the reel fulcrum of crane. It is a steady-state analysis to the reel fulcrum of crane models. These models have played an important role in the assessment of the reel fulcrum of crane performance and the system parameters, but do not reveal the interaction of the reel fulcrum of crane and the wire rope, which fail to be a comprehensive understanding practical system dynamics characteristic. Virtual prototype simulation results will be applied to prototype design and evaluation, and save a lot of manpower and material resources. At the same time, the method has an advantage for dynamics analysis to simulating some dangerous movement conditions, which is hard to be replayed or simulated at the test actual working condition site. In particular, some cases cannot be recurrence in the accident handling process. The simulation results show that the response value. Variable stiffness characteristics of wire rope of hoisting mechanism are implemented successfully through discrete multiple rigid body being applied to the wire rope in this paper. The establishment of the Reel fulcrum dynamic model is based on ADAMS, which realizes the reel fulcrum of crane system coupling modeling. These results show that the model reflects the actual dynamics of the reel fulcrum of crane, and also presents that some of the theoretical analysis results cannot be usually confirmed. © (2014) Trans Tech Publications, Switzerland.