Applied Mechanics and Materials Vol. 302

Abstract: This paper presents the study to find retrofit effect in case of Near-Surface-Mounted Retrofit (NSMR) using Carbon Fiber Reinforcement Polymer (CFRP) plate targeting reinforcement concrete (RC) beam by comparing the previous Externally Bonded Retrofit (EBR) method through experimental analytical works. Three RC beam specimens were made and two of them were retrofitted with CFRP plate by using EBR and NSMR. Also Finite Element (FE) analysis was performed in order to simulate the structural behavior of the beams by considering the bond properties between concrete and CFRP. From the study, it was found that the beam retrofitted with EBR hada reduction of bond capacity in the joint while the beam retrofitted with NSMR had perfect bond capacity.

Abstract: The output displacement error of the single-notch right circular flexure hinge caused by the machining errors is studied. Firstly, two kinds of factors of machining error in single-notch right circular flexure hinge is put forward, namely, the dimensional deviation of three basic parameters of flexure hinge and the angular deviation of the central line of notch-part circular arc. Then, the relationship between the factors of machining error and the output displacement of flexure hinge is analyzed using FEM software ANSYS. The analytic results demonstrate that the minimum thickness and the cutting radius of flexure hinge have strong influence on the output displacement while the results show the angular deviation of the central line of notch-part circular arc around the -axis has almost no influence on the output displacement. The analytical result has an important significance to design flexure hinge.

Abstract: In order to research seismic behavior of flat columns under bilateral cyclic loading with different angles, pseudo-static tests are conducted, which includes three 1:2 scaled flat columns. The height-width ratio of the column section is 5. And the loading directions are 00, 250 and 450 respectively. By observation of the test phenomenon and analysis of the data, the seismic performance of the columns including stiffness, skeleton curves, hysteresis curves, ductility and energy dissipation are obtained. Moreover, finite element program ANSYS is employed to simulate the bearing capacity of specimens. The research shows that with the loading angles increasing from 0 to 45, the strength of the flat column decreased gradually, while the ductility and energy dissipation capacity increase, and the failure mode changed from compression-shear to compression-bending. P-Δ effect becomes evident at lager values of loading angle. The compression-shearing curve of flat column complies with a heart-shape curve.

Abstract: Taking circular gravity foundation of high-rise structure in coral sands as research object, on the basis of mechanical analysis of foundation during inclination, the inclination vibration equation was established. The amplitude of foundation inclination was calculated. The inclination performance function of foundation was established. JC method is used to calculate the reliability index of foundation. Calculation shows that the amplitude of wind velocity has great influence on the reliability index of foundation when the frequency of sinusoidal wind pressure equals the natural frequency of foundation in inclination vibration. In the design of foundation, the natural frequency of foundation in inclination vibration should be made as far away from the frequency of fluctuating wind pressure as possible.

Abstract: Externally bonded reinforcing technique with fiber reinforced polymer (FRP) has been widely used in civil engineering. The performance of the interface between FRP and concrete is one of the key factors affecting the behavior of the strengthened structures. This paper presents a detailed study on the bond-slip mechanism between carbon fiber laminate (CFL) and concrete based on double-shear tests. 8 specimens with different bonded length and width of CFL were tested under static loading. Strain gauges along the CFL face and displacement sensor were used to measure longitudinal strains and slip of the interface. The bond-slip constitutive relation of the interface between CFL and concrete was analyzed with the testing results. Compared with four different bond-slip models, a shear stress-slip model was proposed based on the experimental data.

Abstract: Friction stir channeling (FSC) is a simple method for fabrication of a continuous, integral channel in a monolithic plate, which is carried out in a single pass. The fabricated channels can be applied in heat exchanger industry. In this study, a novel technique was introduced to produce channels in 6061 aluminum alloy which is named as Modified Friction Stir Channeling (MFSC). This technique is derived from Friction stir processing. In this technique, the tool profile and position of tool pin against work piece were designed differently from FSC process. Channels were fabricated with a very regular shape such as rectangular. Comparison between MFSC and FSC showed that fabricated channels, using MFSC process, had better properties relative to fabricated channels by FSC.

Abstract: Modified friction stir channeling (MFSC) is a new approach for fabrication of a continuous, integral channel in monolithic Al plate, which is carried out in a single pass. This technique is derived from Friction Stir Processing (FSP). Tool profile and position of tool pin against work piece were designed differently from conventional Friction Stir Channeling (FSC) process. In MFSC, Fabricated channel with more regular shape than FSC process shows that the channel formation mechanism is different from FSC. So, in this study, in order to understand the formation of channel, material flow in MFSC is investigated using weakened tool pin technique. Moreover, one of the most important channel properties is width of channel. This characteristic affected the channel area and shape of the channel. Width of channel was unknown in FSC process. But in MFSC, a new region is investigated which determines the channel width.

Abstract: The influence of structural elastic deformation on the aerodynamic characterisitcs of large transport aircraft has been researched. A method of static aeroelasticity based on multi-block structural grid of high aspect ratio wing has been established, and then a design method of jig-shape is developed. The technology of RBF interpolation is used to exchange the data of CFD/CSD. Based on RBF&Delaunay technology, a mesh motion method is developed to make the design process less time-consuming, which can be applied to large deformation of multi-block structural grid. The static aeroelastic deformation of a wing-body of large transport aircraft is analyzed. Then the wing-body's jig-shape is designed. Compared the aerodynamic characteristics between design cruise shape and target cruise shape, it shows that the aerodynamic characteristics of design cruise shape is almost equal to target cruise shape and the design process of jig-shape is feasible.

Abstract: Welding residual stress (WRS) has been paid more attention because it would be harmful to safety and intensity of spherical tank. X-ray stress analyzer (XRSA) can be used to non-destructively quantitative analyze WRS. In this study, the real values of Young’s module (E) and Poisson’s ratio (ν) of materials were used to quantitatively calculate. The initial θ0 of materials of welding seam, heat-affected zone and base metal (16MnDR) with zero-stress were detected to analyze influence of quantitative calculation. Moreover, ±5° ψ-oscillation was chosen to use in testing process by XRSA to decrease dispersion of testing data due to large grain size in welding seam and heat-affected zone. Furthermore, XRSA as a non-destructive method will be more used to study WRS of spherical tank, so these results can provide scientific basis for the studying.

Abstract: Downhole sensor data telemetry using acoustic waves along the drillstring helps to know the physical and chemical properties of the formation and drilling fluid in Logging While Drilling. However, complex drillstring channel characteristics and normal downhole drilling operations will often adversely affect the quality of acoustic telemetry. Based on a theoretical channel model, we analyze the effects of transceiver optimal placements on acoustic transmission through a periodic drillstring. Considering the downhole noisy conditions including the surface noise sources, the downhole noise sources and multiple reflection echoes, dual acoustic receivers and an acoustic isolator are analyzed to improve the Signal-to-Noise Ratio and the capacity of the uplink channel. By arranging two receivers spaced one-quarter wavelength apart at receiver ends, the suppression results of one-way downlink noises are evaluated with the aid of the channel transient simulation model. Then the isolating results of uplink noises from drilling bit are investigated, with regard to the isolator placed between the downhole transmitter and a noise source. These methods, in conjunction with the complex drillstring features, show that the uses of the available transceiver design and signal processing techniques can make the drillstring as a waveguide for transmitting downhole sensor information at high data rate.