Novel Four-Cell Lenticular Honeycomb Deployable Boom with Enhanced Stiffness

Composite thin-walled booms can easily be folded and self-deployed by releasing stored strain energy. Thus, such booms can be used to deploy antennas, solar sails, and optical telescopes. In the present work, a new four-cell lenticular honeycomb deployable (FLHD) boom is proposed, and the relevant parameters are optimized. Coiling dynamics analysis of the FLHD boom under a pure bending load is performed using nonlinear explicit dynamics analysis, and the coiling simulation is divided into three consecutive steps, namely, the flattening step, the holding step, and the hub coiling step. An optimal design method for the coiling of the FLHD boom is developed based on a back propagation neural network (BPNN). A full factorial design of the experimental method is applied to create 36 sample points, and surrogate models of the coiling peak moment (Mpeak) and maximum principal stress (Smax) are established using the BPNN. Fatigue cracks caused by stress concentration are avoided by setting Smax to a specific constraint and the wrapping Mpeak and mass of the FLHD boom as objectives. Non-dominated sorting genetic algorithm-II is used for optimization via ISIGHT software.

Mechanical Properties and Structural Optimization of Continuous Welded Rail on Super-Long-Span Suspension Bridges for High-Speed Railway

In order to ensure driving safety and comfort, it is necessary to figure out the complex interaction between continuous welded rail (CWR) and suspension bridges for high-speed railway. A spatial finite element model for a 1092 m main span suspension bridge was established based on the bridge-track interaction theory. A specific correction method was put forward to keep the rail in a zero-stress state when just laid. Three rail expansion joint (REJ) layout schemes were proposed according to practical engineering experience. Both static and dynamic analysis methods were used to evaluate the feasibility of these schemes. The results show that the REJ should be laid at the position with a distance away from the primary beam end, and the beam with more substantial integral stiffness should be preferentially selected. For the recommended scheme, the REJ expansion reaches more than 380 mm under expansion load. The factors affecting the REJ expansion from major to minor are temperature, earthquake, rail fracture, braking, and bending load. The superposition effect of the above factors is suggested to be considered in the selection of REJ range.

Numerical investigation of the cold-formed I-beams bending strength with different web shapes

The wide use of cold-formed sections (CFS) in the field of steel constructions, favored by the multiple advantages they offer (lightness, ease of installation, etc.), has led us to reflect on a new process for manufacture of metal beams allowing the design of very large span hangars and a reduction in instability problems. This paper presents a study of the theoretical and numerical behavior of a large span CFS beam with different webs, a solid web, a triangular corrugated web, and a trapezoidal corrugated web. These beams are stressed by a concentrated bending load at mid-span. Numerical modeling was done using the finite element software ABAQUS. The results were validated with those theoretically found, based on the effective width method adopted in standard EN1993-1-3. The load capacity and failure modes of the beams were discussed. According to numerical and analytical analysis, corrugated web beams perform better than all other sections.

Additional forces on continuously welded rails of a long-span high-speed railway suspension bridge under single effect and multiple effects: A case study

This paper investigates the track–bridge interactions of the Wufengshan Yangtze Bridge, the longest high-speed railway suspension bridge in China. A finite element model of the track and bridge is built using the commercial software ANSYS. The longitudinal additional forces of the track under a single effect and combination effects of temperature rising load, bending load, and braking load are calculated. The numerical results show that strong additional forces appear in the continuously welded rail of the Wufengshan Yangtze Bridge. Temperature effect is the dominant factor for the residual internal forces. The maximum tensile stress is 115.5 MPa and the extreme compressive stress reaches 329.9 MPa. Rail expansion joints are needed for this long-span suspension bridge.

Bendductor—Transformer Steel Magnetomechanical Force Sensor

In this paper, the design and investigation of an innovative force sensor, based on the Villari effect, is presented. The sensor was built from electrical steel, in a pressductor pattern, but working in bending load mode. The results of the experimental research allowed for the evaluation of transducer’s performance, mitigation of measurement hysteresis, and optimization of its functional parameters. Several issues have been examined, among them the selection of supply and measured signals, the measured values’ impact on measurement hysteresis, harmonic analysis, and the selection of proper current waveforms and frequencies. The proposed sensor is robust, made from inexpensive materials, and has high sensitivity, as compared to other magnetoelastic sensors. It has much higher stress sensitivity than other magnetoelastic sensors due to deformation mode. Based on the tests, its measuring range can be defined as 0.5–5 N with a near-linear characteristic, SNR of 46 dB, and 0.11 N uncertainty.

Research on Three-point Bending Mechanical Performance of Square Tube Structure Filled with Foam Aluminum

In this paper, the quasi-static three-point bending experiments are carried out to study the deformation behavior of square tube and square tube filled with foam aluminum. The difference of bending deformation mode, loading characteristics and energy absorption efficiency between tube and foam aluminum filled tube is compared. And the influence of adhesive between the foam aluminum core and the tube wall on the bending deformation of square tube filled with foam aluminum is analyzed. Based on the bending super beam element model of tube structure, the relationship between the moment and rotation of square tube filled with foam aluminum under transverse static loading is analyzed. And the formula for calculating the moment and rotation angle of square tube filled with foam aluminum at three-point bending is obtained. In order to compare the simulation results, theoretical calculation results and experimental results of quasi-static bending, the three-point bending deformation of square tube and filled with foam aluminum under quasi-static and impact loading is simulated by finite element method. The results show that the filling of foam aluminum can improve the bearing capacity and energy absorption performance of the square tube structure. Under the bending load, the deformation degree of the bearing section is greatly reduced, which increases the bearing capacity of the structure and increases the stability of its bending resistance.

Reactive Powder Concrete Beam's Behavior in Flexural : Review

Reactive Powder Concrete can be considered as a special type of concrete in which the coarse aggregate will be eliminated to get a homogenous microstructure with a maximum density for final result. Many researchers presented a state of the art review on reactive powder's production, mechanical properties, durability, development and applications. But the review about structural behavior is hardly to found. Because of importance of this type of concrete and its structural applications. This paper focused on review the researchers that deals with structural behavior of reactive powder concrete beams under bending load. Also review the proposed design equations related with reactive concrete behavior. Before starting a review of strength , stress-strain relation and ductility are presented because of their importance and effect on structure behavior of beams under bending. According to review of previous studies the type of fibers and its content as volumetric ratio, type of pozalanic materials and its content , amount of longitudinal steel reinforcement are main factors that affected the flexural behavior of reinforced Reactive Powder Concrete