Large-scale Network Survivability Mathematical Association Model under Set Pair Analysis Theory

With the expansion of the application field of robots, the use of eight-legged bionic robots to assist or replace human operations in various complex and extreme terrains is constantly being explored. This paper uses octopus as a bionic object, designs an eight-eccentric wheel walking platform, and studies its dynamics, kinematics and trajectory planning. This paper first investigates the development history and research status of multi-legged robots in many countries, analyzes the shortcomings of octa-legged robots, and proposes improved solutions on this basis. Through the bionic of the octopus structure, the Catia software is used to design and establish a three-dimensional model of the octopus-like eight-eccentric wheel robot. By importing the three-dimensional model into the dynamic analysis software Adams for simulation, after adding constraints, driving, torque and contact force, the various functions of the platform are simulated to obtain linear wheel walking, rotary motion, linear leg walking, the parameters of jumping motion and obstacle-crossing motion are drawn into tables for intuitive analysis, and virtual prototype simulation is used to verify the correctness of the established model and trajectory planning. The research in this paper lays a theoretical foundation for the development and application of this eight-eccentric wheel bionic robot.

Study on Material Removal Model by Reciprocating Magnetorheological Polishing

In this study, a new reciprocating magnetorheological polishing (RMRP) method for a flat workpiece was proposed. Based on the RMRP principle and Preston equation, the material removal rate (MRR) model of the RMRP as well as its normal polishing pressure model was established. On this basis, the effects of different technological parameters including workpiece rotation speed, eccentric wheel rotation speed and eccentricity on the MRR of the workpiece were investigated. The K9 optical flat glass was polished with the RMRP setup to verify the MRR model. The experimental results showed that the effect of workpiece rotation speed on the MRR was much greater than that of eccentric wheel rotation speed and eccentricity, and the MRR increased from 0.0115 ± 0.0012 to 0.0443 ± 0.0015 μm/min as workpiece rotation speed rose. The optimum surface roughness reduced to Ra 50.8 ± 1.2 from initial Ra 330.3 ± 1.6 nm when the technical parameters of the workpiece rotation speed of 300 rpm, the eccentric wheel rotation speed of 20 rpm and the eccentricity of 0.02 m were applied. The average relative errors between the theoretical and experimental values were 16.77%, 10.59% and 7.38%, respectively, according to the effects of workpiece rotation speed, eccentric wheel rotation speed and eccentricity on MRR.

Development of Cervical Massage Instrument imitating Manipulation

In order to meet the action effect of pushing, kneading, squeezing, pressing and rolling of nerve root type cervical spondylosis, a new type of cervical massage chair imitating manipulation treatment is developed, which adopts the structural scheme of the combination of massage handwheel and eccentric wheel. Based on NX software, the structure of each part of the cervical massage chair is designed, the virtual prototype is designed, and the finite element analysis of the transmission spindle is carried out. The results show that the structure design is reasonable, the simulation action meets the contra direction synchronous 8-shaped curve track designed by massage handwheel, and the assembly structure is reasonable without interference. Using 3D printing technology, a prototype model was made, which laid a foundation for the follow-up biomechanical analysis and clinical application.

Flexural Performance of a Hybrid Bridge Deck with Pultruded Fibre Reinforced Polymer Composite Sandwich Panels

Hybrid bridge decks with the pultruded fibre reinforced polymer have advantageous properties but easily crack because of their unsatisfactory transverse strength and shear strength. This study proposed a type of bridge deck composed of innovative pultruded fibre reinforced polymer composite sandwich panels. Using four-point bending tests, concentric wheelloading tests and eccentric wheel-loading tests combined with first-order shear deformation theory, this study investigated the failure mode, flexural capacity, deformation and ductility of hybrid bridge decks under different working conditions. Under four-point bending and concentric wheel loading, the primary failure modes for this hybrid bridge deck were shear failures along the fibre direction and buckling failure of the upper panel. Under eccentric wheel loading, the primary failure mode was a torsional failure due to the eccentric load. The bearing capacities of the hybrid bridge deck under the three working conditions were 3.8, 3.5 and 3.2 times the service load of a Class I vehicle load, respectively. Besides, the hybrid bridge deck remained in the linear elastic stress state at 2.6 times the service load, indicating that this hybrid bridge deck withstands relatively large vehicle overload without visible damage. The ductility values of this hybrid bridge deck under the three working conditions were 1.79, 2.09 and 2.00, respectively, which are higher than the values for an ordinary pultruded bridge deck. Therefore, the proposed design has the relatively good energy-dissipating capacity, which improves the emergency capacity of the bridge deck.

Resonance and Cancellation in Torsional Vibration of Monosymmetric I-Sections Under Moving Loads

This paper is concerned with the lateral and torsional coupled vibration of monosymmetric I-beams under moving loads. To this end, a train is modeled as two subsystems of eccentric wheel loads of constant intervals to account for the front and rear wheels. By assuming the lateral and torsional displacements to be restrained at the two ends of the beam, both the lateral and torsional displacements are approximated by a series of sine functions. The method of variation of constants is adopted to derive the closed-form solution. For the most severe condition when the last wheel load is acting on the beam, both the conditions of resonance and cancellation are identified. Once the condition of cancellation is enforced, the resonance response can always be suppressed, which represents the optimal design for the beam. Since the condition for suppressing the torsional resonance is exactly the same as that for the vertical resonance, this offers a great advantage in the design of monosymmetric I-beams, as no distinction needs to be made between the suppression of vertical or torsional resonance.