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In this study, a series of numerical calculations were performed to investigate the lateral behavior of piles in slopes and in horizontal ground. First, a numerical model is created and then verified by comparing the numerical results with the results of model tests. The numerical results agree well with the results of model tests. Second, numerical calculations of different slopes were conducted to explore the effect of slope angle on the horizontal displacement of pile and bending moment. Then, the effect of slope angle on the foundation stiffness proportional coefficient m is investigated. The stress distribution of soil around the pile and the deformation of pile at different slope angles are also compared. Finally, the p–y curves of the different slope angles are compared. An improved p–y method is proposed to consider the effect of slope angle based on the numerical results. The results show that the bearing capacity of piles decreases with an increase in slope angle. The horizontal displacement of pile nonlinearly decreases along the pile body with the depth of pile. The bending moment of piles increases along the pile body with an increase in pile depth, and until 0.5 times of the pile length, the bending moment reaches the maximum value. As the slope angle increases, the maximum of bending moment tends to decrease. The distance from the slope toe to the pile section has a little influence on the pile bending moment and horizontal displacement. With an increase in slope angle, the horizontal foundation coefficient m gradually decreases. [ABSTRACT FROM AUTHOR]

The high-payload transporter is a key part of the multipurpose deployer, which is important for realizing the remote handling of tokamaks. This paper presents an analysis of the key joint between the high-payload transporter and the design of the test platform. The kinematic, structural, and load characteristics of the main joints of a heavy-duty manipulator were analyzed according to the peculiarity of high precision, large length, and heavy load of the high-payload transporter. Joint No. 4 (J4) was determined to be the key joint of the high-payload transporter. The peak torque, bending moment, and shear force of J4 under working conditions and seismic conditions were determined via numerical simulations. The functions and key technical parameters of the test platform for J4 were determined according to the test analysis results and numerical simulation. The structure of the test platform was designed, and its working principle was described. [ABSTRACT FROM AUTHOR]

To further reduce the power of exciter in the common fatigue testing methods and increase the testing frequency to decrease the fatigue testing time, this paper proposes an improved fatigue testing method—Tug Fatigue Testing system (TFTs). The advantages of this new fatigue testing method are low power and high testing frequency of its exciter due to no exciter with moving masses attached to the blade. In TFTs, exciters mounted on the ground or fixed bracket can be used to excite the blade in the uniaxial or biaxial fatigue test. In this paper, the mechanical model of TFTs is established to compare the motor power required by exciters in TFTs and the inertial exciters and the shear load on the blades in both ways. Furthermore, a test of a 56.5 m blade will be performed to verify the feasibility of the new method. In addition, the bending moment distribution of an 80 m blade excited by TFTs was measured and compared with the bending moment distribution of the same blade excited by inertial resonance excitation to evaluate its excitation effect. The test results prove that this improved method needs lower power of exciter, produces smaller shear loads, and provides a higher test frequency in the flap-wise test direction than common inertial resonance excitation. Biaxial fatigue tests can also be conducted by this new method. [ABSTRACT FROM AUTHOR]

A tool system integrated with machining and measurement is constructed by using thin film strain sensors and tool integration technology, which provides a new research method for studying the machining mechanism and automatic monitoring of the machining process. In this paper, three kinds—elastic sleeve type, fast insert type, and insert type—of tool cutting force measurement systems of the turning tool embedded with thin-film micro-sensors are designed. High strain sensitivity can be obtained through setting the elastic region of the tool bar on the premise of meeting the tool strength and stiffness. The system can realize integration between the thin-film strain sensor and tool bar quickly and efficiently. It is simplified as a cantilever beam structure for analysis after setting the shape of the sensor elastic substrate as a rectangle. The expression between strain and deflection of the elastic substrate is established when the free end is subjected to tangential force and bending moment, and the influence of the substrate's structural parameters on the deflection is analyzed. In order to further improve the strain effect, six kinds of other shapes of the substrate structure are optimized, deducing the expression between the structure parameters and deflection; the corresponding substrate structure atlas is established, comparing and analyzing the deflection of the rectangular structure substrate. Five kinds of metal substrate materials are selected. In the functional film system of the thin-film strain sensor, the scheme of aluminum oxide and titanium nitride as the transition layer, silicon nitride as the insulating layer, and Ni–Cr alloy as the resistance grid layer is adopted. The research results show that this scheme can improve the adhesion between the insulating layer and the substrate, improve the resistance sensitivity coefficient of the sensor, and meet the application requirements of the cutting force measurement system. [ABSTRACT FROM AUTHOR]

For the study of the double wave configuration for the dynamic power cable of a Floating Offshore Wind Turbine (FOWT) in shallow water, this paper presented a comparison of the hydrostatic and hydrodynamic performance between a lazy wave and a double wave configuration. The double wave shape's parametric presentation was first developed based on an extension of a previous parametric lazy wave shape. An aero-hydro-servo-elastic integrated model fully coupling the FOWT and the dynamic power cable was then proposed in the SIMO/RIFLEX code for numerical simulation. Subsequently, the strain-cycle curve and the rain flow counting method were employed to estimate the copper conductor's fatigue damage. The bending moment was proved to provide the major fatigue contribution. The results showed that the double wave offered superior performance than the lazy wave. The second arc of the double wave configuration was proved critical for suffering high curvature, tension, and fatigue damage. A lower position and less hogged wave arc were suggested for the determination of the double wave shape. [ABSTRACT FROM AUTHOR]

To investigate the effects of breathing cracks on the dynamic characteristics, i.e., natural frequencies, vibration displacement, slope angle, and bending moment, of a drilling riser, a time-domain finite element method based on the fracture mechanics theory is developed. The correctness of the proposed method is verified, and the performance of the different dynamic characteristics for crack identification is evaluated. First, the influence of the breathing and open cracks on natural frequencies is explored. The maximum frequency shifts vs crack location and water depth are studied. The results of the small difference of natural frequencies between intact and cracked risers illustrate that the traditional frequency-based crack-detection method is not applicable for the risers. Second, the time-domain motions, orbit plots, Poincaré maps, and fast Fourier transform diagrams are extracted for discussing the effects of the breathing and open cracks and crack depth and location. Finally, the second and fourth derivatives of the root-of-mean-square (RMS) of the dynamic response characteristics are defined for crack identification. It is found that the moment RMS has a good performance in single- and multiple-crack identifications and that not only locations but also degrees of the breathing cracks can be well detected by the proposed indices. In short, several conclusions drawn are a benefit for the safety of a serviced drilling riser system. [ABSTRACT FROM AUTHOR]

According to the lack of theoretical research on the spatial effect of the foundation pit, the concept of the reasonable arch curve (bending moment on the curve is zero everywhere) is introduced to establish a new three-dimensional instability failure theoretical model of the water-rich foundation pit. Taking the K6 + 650 ∼ K6 + 880 section of the GUI River Foundation Pit as an example, the active earth pressure acting on the supporting structure per unit length, the critical length–depth ratio, the main influence range, and the influence coefficient of spatial effect are calculated and compared with previous research results and field monitoring data, in order to explore the influence law of the length, depth, and moisture content of soil layers on the spatial effect. The results show the following: (1) When the length–depth ratio is greater than 1, the foundation pit presents the failure mode of the end arch curve and middle straight line, and when the length–depth ratio is greater than 3, the main influence range has a linear relationship with the depth and a negative correlation with the moisture content, but little relationship with the length. (2) The active earth pressure is approximately a quadratic function of the depth, and there is a more than 16% increase when the moisture content increases from 21% to 25%. (3) The change law of the horizontal displacement of the pile top monitored verifies the rationality and progressiveness of the new instability failure model. Through this study, the spatial effect revealed can provide the theoretical basis for pile support of the foundation pit. [ABSTRACT FROM AUTHOR]

In this study, based on the elastic foundation beam theory, a local elastic foundation model has been developed. Using the model, the mechanical characteristics of the effect of tunnel-filled karst on the lining structure has been investigated. Incorporating the characteristic of the karst area, the formulas for the displacement, bending moment, and shear force of an equivalent beam have been derived. By applying the formulas to a beam under different working conditions, such as different cavern sizes and different compression modulus ratios of the filling media, analyses of the mechanical states have been carried out. The results show that if the compression modulus ratio of different filling media is close to unity, the effect of the cave on the lining structure is very small. On the other hand, if the ratio is much less than unity, the effect is more significant. The effect on the stability of the lining structure is greater for the larger caves, and smaller for the smaller caves. For the tunnel bottom equivalent beam, its bending point is at the point where the cave is in contact with the surrounding rock. Further, the maximum shear force is at the contact surface. For a beam that is closer to the karst, the displacement is larger. Under this situation, the beam section is in an adverse force state and prone to cracks. The results from this study can be used as a significant guide for the design, maintenance and construction of a tunnel which has a cavern at the base of the tunnel. [ABSTRACT FROM AUTHOR]

In recent years, the concept of the Acoustic Black Hole has been developed as an efficient passive, lightweight absorber of bending waves in plates and beams. Theory predicts greater absorption for a higher thickness taper power. However, a higher taper power also increases the violation of an underlying theory smoothness assumption. This paper explores the effects of high taper power on the reflection coefficient and spatial change in wave number and discusses the normalized wave number variation as a spatial design parameter for performance, assessment, and optimization. [ABSTRACT FROM AUTHOR]