Effect Of Manufacturing Tolerances Research Articles

Mechanical integrity of tubing string in high‐temperature and high‐pressure ultra‐deep gas wells based on uncertainty theory

AbstractDuring the manufacturing process of tubing and casing, manufacturing deviations can occur in quality parameters, such as yield strength, outer diameter, and wall thickness, which can lead to uncertainty in the actual strength of the tubing string. Specifically, tubing string failures periodically occur in high‐temperature, high‐pressure, and ultra‐deep gas wells owing to the uncertainty in string strength, attenuation of high‐temperature material properties, and influence of complex load fluctuations. Therefore, in this study, Monte Carlo method is adopted to simulate the local fluctuation of downhole actual load, and the load variation rule of tubing string in high‐temperature and high‐pressure ultra‐deep well is obtained. By considering the effect of manufacturing tolerance and corrosion, variation law of string strength is obtained. Additionally, the influence of load, temperature, manufacturing tolerance, and other uncertainties on the strength and stress of the tubing string is analyzed, and a quantitative evaluation method for the mechanical integrity of the tubing string is established. The calculation results show that the uncertainty of complex loads and influence of high temperature increase the failure probability of the mechanical integrity of tubing string. Furthermore, a failure risk can potentially exist under conditions wherein conventional verification results denote no failure. It is determined via sensitivity analysis that temperature, corrosion rate, and steel grade are the main factors for the failure of the tubing string mechanical integrity. By considering the influence of high temperature, the failure probability of the tubing string is increased by 25.33% when compared to the original basis. However, considering the manufacturing tolerance of tubing string, the actual yield strength of tubing string is higher than the nominal yield strength, which reduces the failure probability of the tubing string. This implies that reduction of the subjective influence in the risk assessment process can lead to precise and quantitative analysis of the failure risk of the tubing string mechanical integrity and optimization of the structure of the tubing string in high‐temperature, high‐pressure, and ultra‐deep gas wells.

Retraction Notice: Reliability Analysis on Gear Contact Fatigue Strength Considering the Effect of Tolerance

Tolerance allocation influences product performance especially for miniature precise assembly device. The purpose of this paper is to explore an approach to optimize manufacturing tolerances by combining the reliability of product performance indicators under actual working condition. The paper describes the principle and ways of tolerance handling in the finite element control equations for the displacement and stress, and then introduces the implementation of Monte-Carlo Finite Element Analysis method. We illustrate this method on a gear-tooth of port-cleaning-equipment gear pump and carry out the reliability analysis on gear contact fatigue strength considering the effect of manufacturing tolerance, and a sensitivity analysis is also performed to identify the key tolerances and improve them in order to attain the expected reliability.

Optimization of Spherical Roller Bearing Design Using Artificial Bee Colony Algorithm and Grid Search Method

Bearing standards impose restrictions on the internal geometry of spherical roller bearings. Geometrical and strength constraints conditions have been formulated for the optimization of bearing design. The long fatigue life is one of the most important criteria in the optimum design of bearing. The life is directly proportional to the dynamic capacity; hence, the objective function has been chosen as the maximization of dynamic capacity. The effect of speed and static loads acting on the bearing are also taken into account. Design variables for the bearing include five geometrical parameters: the roller diameter, the roller length, the bearing pitch diameter, the number of rollers, and the contact angle. There are a few design constraint parameters which are also included in the optimization, the bounds of which are obtained by initial runs of the optimization. The optimization program is made to run for different values of these design constraint parameters and a range of the parameters is obtained for which the objective function has a higher value. The artificial bee colony algorithm (ABCA) has been used to solve the constrained optimized problem and the optimum design is compared with the one obtained from the grid search method (GSM), both operating independently. Both the ABCA and the GSM have been finally combined together to reach the global optimum point. A constraint violation study has also been carried out to give priority to the constraint having greater possibility of violations. Optimized bearing designs show a better performance parameter with those specified in bearing catalogs. The sensitivity analysis of bearing parameters has also been carried out to see the effect of manufacturing tolerance on the objective function.

Reliability Analysis on Gear Contact Fatigue Strength Considering the Effect of Tolerance

Tolerance allocation influences product performance especially for miniature precise assembly device. The purpose of this paper is to explore an approach to optimize manufacturing tolerances by combining the reliability of product performance indicators under actual working condition. The paper describes the principle and ways of tolerance handling in the finite element control equations for the displacement and stress, and then introduces the implementation of Monte-Carlo Finite Element Analysis method. We illustrate this method on a gear-tooth of port-cleaning-equipment gear pump and carry out the reliability analysis on gear contact fatigue strength considering the effect of manufacturing tolerance, and a sensitivity analysis is also performed to identify the key tolerances and improve them in order to attain the expected reliability.

Comparison of Effects of Dimensional Manufacturing Tolerances and Journal Out-of-Roundness on Stability of Hydrodynamic Journal Bearing System

The manufacturing tolerances of a hydrodynamic journal bearing system are inevitable in manufacturing process. To examine and understand the effect of manufacturing tolerances on the system stability can help engineers to confidently choose reasonable tolerances at design stage. This study presented a theoretical analysis method to determine and compare the effects of dimensional manufacturing tolerances and journal out-of-roundness on system stability by Taguchi method. The results show that the journal out-of-roundness has the most significant effect on the system stability and the journal out-of-roundness appears to stabilize the system. The authors suggest that both dimensional manufacturing tolerances and journal roundness should be taken into account in the design of cylindrical journal bearings.

The effects of dimensional manufacturing tolerances on stability of a symmetric hydrodynamic journal bearing rotor system – an experimental investigation

The importance of gross dimensions on the design and operation of hydrodynamic journal bearing system are widely understood, however, the effects of manufacturing tolerances have only been macroscopically analysed. Building on previous theoretical analyses, an experimental investigation on the effect of dimensional manufacturing tolerances is presented. Importantly, the study looks at individual effects and combined effects. The experimental data suggested that the error created by manufacturing tolerances in estimating the onset of oil film instability can be as much as ±20 per cent, depending on the steady state operating position. This finding shows that in order to minimize the effect of manufacturing tolerances on system stability, the hydrodynamic journal bearing system should be designed to operate at a modified Sommerfeld number greater than 0.1, where the effects of manufacturing tolerances on system stability are negligible.

A theoretical investigation of the use of 2k factorial analysis to determine the effects of dimensional manufacturing tolerances on the stability of hydrodynamic journal bearing systems

Manufacturing tolerances and deviations from design parameters are inevitable in real hydrodynamic journal bearing systems. Normally, the stability of the system is assessed on the design parameters alone; the effects of deviations are assumed to be negligible and only the effects of gross changes are considered. In isolation, a single deviation may not demonstrate a significant effect, but in combination with other deviations, the effect may be large. This study presents a 2 k factorial analysis of the effects of manufacturing tolerances on system stability. It is further used to determine which tolerance, or combination of tolerances, is the most significant. The results show that manufacturing tolerances, and combinations thereafter, do have a significant effect on system stability, and they influence the system stability in different ways. The study also identified a region where system stability is insensitive to deviations. To enable visualization of the effects, a modified Sommerfeld number and new stability map are presented. Furthermore, the overall philosophy of using a ‘design of experiments’ approach to the determination of system stability has been vindicated. A later paper will compare the results from this study to those from experimental results.

Highly selective bandpass filter based on substrate integrated waveguide

A novel highly selective six-pole elliptic filter based on a substrate integrated waveguide (SIW) is proposed for the first time. The filter is composed of two planar SIW extend doublets. The modular design approach based on cascading small building blocks is adopted to reduce the effect of manufacturing tolerance on the performance of the filter. The proposed filter can produce four finite transmission zeros, and has an excellent stopband rejection characteristic. Measured results are presented and compared with results simulated by a high frequency structure simulator. Good agreement between simulated and measured results is observed.