Mapping Relation between Contour Error Components of Crankshaft Pin Journal and Axis Position Control Error of Oscillating Grinding Machine

Automatic crankshaft production lines require high reliability and accuracy stability for the oscillating grinding machine. Crankshaft contour error represent the most intuitive data in production field selective inspection. If the mapping relation between the contour error components of the crankshaft pin journal and the axis position control error of the oscillating grinding machine can be found, it would be great significance for the reliability maintenance of the oscillating grinding machine. Firstly, a contour error decomposition method based on ensemble empirical mode decomposition (EEMD) is proposed. Secondly, according to the contour generating principle of the pin journal by oscillating grinding, a calculation method to obtain the effect of the axis position control error of the oscillating grinder on the contour error of the pin journal is proposed. Finally, through the grinding experiments, the error data are acquired and measured to calculate and decompose the contour error by using the proposed methods for obtaining the mapping relation between the crankshaft pin journal contour error and the axis position control error. The conclusions show that the proposed calculation and decomposition methods can obtain the mapping relation between the contour error components of the crankshaft pin journal and the axis position control error of the oscillating grinding machine, which can be used to predict the key functional component performance of the machine tool from the oscillating grinding workpiece contour error.

Flexible Fiber Fabric for FRP–Concrete Connection of Thin Hybrid Slabs

In order to combat corrosion issues, several studies on progressively replacing steel reinforcement elements with composite ones have been conducted in recent years. Hybrid steel–concrete thin slabs in which the steel acts as formwork are also candidates for update in the coming years. Achieving a reliable connection between fiber-reinforced polymer (FRP) and cast-in-place concrete is key to promoting this technology. This study analyzed different connection systems and proposes the novel approach of embedding a flexible fiber fabric as a superficially distributed connector between concrete and FRP. Eight specimens with four different connection strategies were tested using an experimental modal analysis and a quasi-static three-point bending test. The impact of the connection system on the vibrational response, flexural ultimate load, moment response, neutral axis position, shear and dissipated energy was obtained and compared. The results show that the use of an embedded mesh increases the frictional mechanism and produces the best performance in terms of load-bearing capacity and ductility.

Improvement and Assessment of the Plastic Collapse Bending Moment Equations in Circumferentially Cracked Pipe

The plastic collapse bending moment in a pipe cross-section with a circumferential crack is defined in ASME B&PV Code Section XI, Appendix C using simplified equilibrium equations by approximating the pipe mean radius Rm and the neutral axis angle β. In previous papers it was demonstrated by the authors that, for externally cracked pipes, those simplified equilibrium equations are not conservative and hence improved equations were developed and proposed which account for the cracked pipe ligament mean radius Rmc. In this paper, it is demonstrated that the accuracy of the collapse bending moment equation can be refined by taking into account the neutral axis position Yna of the cracked pipe section. This leads to exact collapse bending moment equations without any approximation on the pipe mean radius Rm nor on the neutral axis angle β. In this framework, it is shown that, for externally cracked pipes, the Appendix C equations could lead to more than 20% less conservative collapse bending moment than with the exact equations. An extended finite element method analysis completes this study to assess the relevance of the model used to determine the plastic collapse bending moment.

Seasonal Variation of the Surface Kuroshio Intrusion into the South China Sea Evidenced by Satellite Geostrophic Streamlines

The long-term satellite altimeter and reanalysis data show that large seasonal variations are associated with geostrophic Kuroshio intrusion, but not with the current intensity, width and axis position east of Philippine. To address this issue, we examine the seasonal variability of surface intrusion patterns by a new streamline-based method. The along-streamline analysis reveals that the seasonality of geostrophic intrusion is only attributed to the cyclonic shear part of the flow, while the anticyclonic shear part always leaps across the Luzon Strait. A possible physical mechanism is proposed to accommodate these seasonal characteristics based on globally the vorticity (torque work) balance between the basin-wide negative wind stress curl and the positive vorticity fluxes induced by the lateral wall, as well as locally loss of balance between the torques of frictional stresses and normal stresses owing to the boundary gap. Through modifying the nearshore sea surface level, the northeasterly/southeasterly monsoon increases/decreases the positive vorticity fluxes in response to global vorticity balance, and simultaneously amplifies/alleviates the local imbalance by enhancing/reducing the positive frictional stress torque within the cyclonic shear layer. Therefore, in winter when the positive torque is large enough, the Kuroshio splits and the intrusion occurs, while in summer the stress torque is so weak that the entire current keeps flowing north.

STUDY OF THE ELECTRONIC TOTAL STATION TRAVEL FOCUSING LENS MOVEMENT INFLUENCE ON THE SIGHTING AXIS POSITION

When carrying out geodetic work inside production shops or on a construction site, it is necessary to significantly change the focusing of the telescope. Refocusing the telescope can lead to a shift in the sighting axis, and, accordingly, to a decrease in the accuracy of angular measurements. The article presents the results of laboratory studies to determine the horizontal error of collimation and vertical index error of the Leica total station for distances from 2 to 84 m. Therefore, after checking the collimation and vertical index error and automatically taking into account their influence, it is allowed performing geodetic measurements at one position of the vertical circle. In particular, this makes it possible to speed up the execution of fan-shaped trigonometric leveling with short sights, which is performed when observing the settlements of the foundations of industrial buildings and structures.

The Dynamical Structure of a Warm Core Ring as Inferred from Glider Observations and Along-Track Altimetry

This study investigates the vertical structure of the dynamical properties of a warm-core ring in the Gulf of Mexico (Loop Current ring) using glider observations. We introduce a new method to correct the glider’s along-track coordinate which is, in general, biased by the unsteady relative movements of the glider and the eddy, yielding large errors on horizontal derivatives. Here, we take advantage of the synopticity of satellite along-track altimetry to apply corrections on the glider’s position, by matching in situ steric height with satellite-measured sea surface height. This relocation method allows to recover the eddy’s azimuthal symmetry, to precisely estimate the rotation axis position, and to compute reliable horizontal derivatives. It is shown to be particularly appropriate to compute the eddy’s cyclo-geostrophic velocity, relative vorticity, and shear strain, which are otherwise out of reach when using the glider’s raw traveled distance as an horizontal coordinate. The Ertel potential vorticity (PV) structure of the warm core ring is studied in details, and we show that the PV anomaly is entirely controlled by vortex stretching. Sign reversal of the PV gradient across the water column suggests that the ring might be baroclinically unstable. The PV gradient is also largely controlled by gradients of the vortex stretching term. We also show that the ring’s total energy partition is strongly skewed, with available potential energy being 3 times larger than kinetic energy. The possible impact of this energy distribution on the Loop Current rings longevity is also discussed.

Measurement and Comparison of Bracket Transfer Accuracy With Different Indirect Bonding Techniques: An In Vitro Study

Objective: To measure and compare bracket transfer accuracy of 3 indirect bonding (IDB) techniques. Material and Methods: Three IDB techniques were studied using polyvinyl siloxane (PVS) putty, vacuum-form (VF), and glue gun (GG). A total of 120 orthodontic stone models were fabricated with die stone, out of which bonding was done on 60 working models and transferred to other 60 patient models. One quadrant was selected for each technique. Digital photography was used to measure the mesiodistal ( X-axis), occlusogingival ( Y-axis), and faciolingual ( Z-axis) position of each bracket on the working and patient models. Results: All the 3 IDB techniques have a very good bracket transfer accuracy. On comparing individual planes, greatest accuracy was seen in GG on X-axis, VF on Y-axis, and VF/PVS on Z-axis. Points A and B were compared for bracket rotation and the mean differences were insignificant indicating that there was no significant amount of rotation in 3 IDB techniques. Conclusions: We can say that all 3 IDB techniques had a very high bracket transfer accuracy. Out of the 3 IDB techniques VF was the most accurate, whereas PVS was the least accurate technique. The selection of technique should be based on tray cost and fabrication time.

Design and analysis of the mandrel structure for a composite S-shaped inlet

Automated fiber placement (AFP) combining with the autoclave curing process is the main manufacturing method for large-scale rotary composite parts. During the forming process, the mandrel plays an important role that affects the forming quality of the part directly. In this study, design and analysis of the mandrel structure for a composite S-shaped inlet are carried out. The preforming process of the rotary composite part using the AFP technique is introduced first. Then, design principles of the shaft are presented and applied to the shaft design for the mandrel of the S-shaped inlet, which then is transformed into an optimization problem. The internal penalty function method is adopted to solve this optimization problem in order to obtain the optimal axis position and axle diameter. Moreover, detailed structure design of the mandrel is proposed which takes the demolding into consideration, and the wall thickness is designed considering the total weight and the stiffness. The static analysis and modal analysis are also carried out by the finite element method to verify the feasibility of the proposed mandrel structure.