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181.
182.
切槽车刀工作环境封闭,工作状况恶劣,使得刀具温度高和刀具磨损的问题尤为突出。运用数值计算方法建立了硬质合金切槽车刀车削加工钛合金环槽过程模型,基于传热学和Usui磨损理论计算车削过程中刀具最高温度和刀具磨损速率。对环槽车削过程的热力耦合计算结果进行分析,获得了刀具在切削过程中的温度及磨损速率的变化规律。建立了刀具温度和磨损速率的预测模型,运用遗传算法对预测模型进行求解,得到满足要求的工艺参数组合。结果表明,刀具温度和磨损速率与工艺参数之间关系密切。通过应用优化算法对切削工艺参数进行优化,使得目标函数值增加了30%,运用切削实验验证了优化后的工艺参数能够有效提高硬质合金切槽车刀的性能。 相似文献
183.
184.
Chang?Woo?Lee Hyun?Kyoo?Kang Kee?Hyun?ShinEmail author 《Journal of Mechanical Science and Technology》2004,18(12):2174-2181
The metal processing system usually consists of various components such as motors, work rolls, backup rolls, idle rolls, sensors,
etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is, therefore,
necessary to diagnose the faults of the components to detect and prevent a system failure. Especially, the defects in a work
roll are critical to the quality of strip. In this study, a new 3-D diagnosis method was developed for roll shape defects
in rolling processes. The new method was induced from analyzing the rolling mechanism by using a rolling force model, a tension
model, the Hitchcock’ s equation, and measurement of the strip thickness, etc. Computer simulation shows that the proposed
method is very useful in the diagnosis of the 3-D roll shape. 相似文献
185.
A compound scheme is proposed to compensate the effect of nonlinear friction disturbance on the control precision of a three-axis inertially stabilized platform (ISP) for aerial remote sensing applications. The scheme consists of friction parameters identification and adaptive compensation. A LuGre model-based ISP friction model is first developed. Then, a comprehensive experimental scheme is proposed to obtain the static friction parameters. Further, the dynamic parameters are identified by experiments and dynamic optimization. On the basis of identified parameters and Lyapunov stability theory, a backstepping integral adaptive compensator is designed to compensate the nonlinear friction disturbance. Simulations and experiments are carried out to validate the scheme. The results show that the compound scheme can accurately obtain the friction parameters and improve the control precision and stability of ISP. 相似文献
186.
187.
新型Ti5553合金是一种很难加工的钛合金.分析了Ti5553合金的切削加工性,提出了切削刀具、切削参数和装夹方式的选择,可以为从事Ti5553合金工件加工人员提供一定的帮助. 相似文献
188.
Continuous monitoring of soil properties using an instrumented roller compactor requires models that can capture the essential features observed during drum/soil vibration. This paper presents the results of lumped parameter modeling of the drum/soil system together with data from complex nonlinear behavior observed experimentally during operation on sandy soil. Model parameters and response were developed using experimental data collected over a wide range of operating frequencies. Three and four-degree-of-freedom (DOF) models with linear and nonlinear soil elements were investigated. The results showed that a 3DOF model incorporating the soil, drum, and frame of the roller was successful in capturing behavior during coupled drum/soil vibration and during decoupling (i.e., loss of contact between drum and soil). Modeling the drum/soil decoupling accounted for most of the experimentally observed nonlinearity. The addition of nonlinear soil stiffness due to the curved drum effect and due to strain hardening soil behavior accounted for additional nonlinearity observed experimentally. Experimentally observed drum rocking during coupled drum/soil vibration was successfully modeled with a 4DOF drum-frame model. The analysis also revealed that commonly observed heterogeneous soil conditions give rise to a transient response that can have a significant influence on vibration behavior. 相似文献
189.
This paper presents a Bayesian hypothesis testing-based probabilistic assessment method for nonparametric damage detection of building structures, considering the uncertainties in both experimental results and model prediction. A dynamic fuzzy wavelet neural network method is employed as a nonparametric system identification model to predict the structural responses for damage evaluation. A Bayes factor evaluation metric is derived based on Bayes’ theorem and Gaussian distribution assumption of the difference between the experimental data and model prediction. The metric provides quantitative measure for assessing the accuracy of system identification and the state of global health of structures. The probability density function of the Bayes factor is constructed using the statistics of the difference of response quantities and Monte Carlo simulation technique to address the uncertainties in both experimental data and model prediction. The methodology is investigated with five damage scenarios of a four-story benchmark building. Numerical results demonstrate that the proposed methodology provides an effective approach for quantifying the damage confidence in the structural condition assessment. 相似文献
190.
Sushil K. Singh 《Canadian Metallurgical Quarterly》2008,134(1):107-110
A method is proposed for identifying the head loss from the early drawdowns at the pumped well and an observation well. The new method is computationally simple and the calculations can be performed even on a hand-held calculator. The previously proposed methods for identifying the head loss requires a long duration pumping test, while the new method requires only a short duration pumping test. The use of the proposed method would save time and money and would be of help to field and practicing engineers. A nondimensional coefficient of head loss is also proposed, which permits a meaningful comparison of the efficiency conditions of different wells. 相似文献