scholarly journals Experimental verification of new features of bearing operation under combined loading conditions

2021 ◽  
Vol 17 (3) ◽  
pp. 278-287
Author(s):  
Valeriy V. Kirilovskiy ◽  
Yuri V. Belousov
Keyword(s):  
Theoretical Model ◽  
Experimental Verification ◽  
Traditional Method ◽  
Geometric Shape ◽  
Experimental Results ◽  
Combined Loading ◽  
Loading Conditions ◽  
Structural Elements ◽  
Elastic Line ◽  
Bearing Assembly

Bearing units of lifting machines, products of construction, road, aviation, space and other branches of technology are very important structural elements, since the failure of even one bearing can cause the failure of the entire product. The results of experimental verification of the theoretical model of bearing operation under combined loading conditions are presented. The behavior under load of bearing units in the most general case can be represented by a sequence of five design schemes, expressed in the form of five statically indeterminate beams. The purpose of the experiments was to test this model under real loading conditions. The experiments were based on the analysis of the geometric shape of the curved elastic line, which the shaft of the bearing assembly acquires under load. The experimental results confirmed the validity of the model and showed that the previously generally accepted model of a two-support beam is not implemented. The conclusion is confirmed that in responsible lifting machines, as well as in responsible products of construction, road, aviation, space and other branches of technology, it is impractical to calculate bearings according to the traditional method, since an erroneous value of bearing durability can be obtained, overestimated from 28.37 to 26.663.9 times.

Research on VSC-HVDC Based on Modular Multilevel Converter Technique

2014 ◽  
Vol 577 ◽  
pp. 588-593
Author(s):  
Si Yu Chen ◽  
Ya Lou Li ◽  
Xiao Bo Hu ◽  
Li Zhao ◽  
Chao Xi Chen
Keyword(s):  
Theoretical Model ◽  
Equivalent Circuit ◽  
Control Strategy ◽  
Traditional Method ◽  
Experimental Results ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Hvdc System ◽  
Proposed Model ◽  
Working Principle

This paper introduces the topology and working principle of modular multilevel converter, simplifying its equivalent circuit before obtaining virtual equipotential. On the ground of the theoretical model of equivalent circuit, MMC-HVDC could adapt the same control strategy as the traditional method. So, on the platform of PSCAD/EMTDC, an eleven level MMC Dual-infeed HVDC system is established and nearest level modulation is adopted as its control strategy to sort voltage sharing of the modules. Experimental results prove the validity of the proposed model.

Simulating adhesion of wet fabrics to water: Gravity of liquid bridge-based theoretical model and experimental verification

2016 ◽  
Vol 87 (7) ◽  
pp. 769-779 ◽  
Author(s):  
Lin Lou ◽  
Jianfei Xie ◽  
Feng Ji ◽  
Yiping Qiu ◽  
Xiaohang Zhu ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Human Skin ◽  
Experimental Verification ◽  
Liquid Bridge ◽  
Adhesion Force ◽  
Body Movement ◽  
Experimental Results ◽  
Potential Solution ◽  
Adhesion Forces ◽  
Fabric Surface

Wet fabric bothers everyone as it sticks to the skin, hinders body movement and brings discomfort and awkwardness on many occasions. Much has to be done to evaluate this adhesion of a wet fabric to human skin for minimizing the discomfort resulting from this phenomenon. In this study, an improved measurement is developed to test and distinguish the adhesion forces of different materials under controlled conditions. A new and improved theoretical model is proposed to estimate the adhesion force based on the gravity of the liquid bridge that formed beneath the fabric. The theoretical values are reasonably consistent with the experimental results. A potential solution is also proposed for reducing the volume of the liquid bridge in designing a less adhesive fabric by constructing hydrophobic protrusions to the fabric surface.

scholarly journals Experimental Verification of Anomalous Forces on Shielded Symmetrical Capacitors

2020 ◽  
Vol 12 (2) ◽  
pp. 33
Author(s):  
Elio B. Porcelli ◽  
Omar R. Alves ◽  
Victo S. Filho
Keyword(s):  
Theoretical Model ◽  
Quantum Entanglement ◽  
Experimental Verification ◽  
Good Accuracy ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Ionic Wind ◽  
Dipole Force ◽  
Electric Potentials ◽  
Positive Results

In this work, we measured the magnitude of forces raised from the operation of symmetrical capacitor devices working in high electric potentials. Our experimental measurements were realized with basis on an improved setup which aimed significant reduction of ionic wind by means of an efficient shield. We observed small variations of the device inertia within an accurate range and we confirmed with good accuracy that the experimental results can be explained by a generalized quantum entanglement hypothesis which provides us a theoretical model for a macroscopic dipole force raised by the myriad of microscopic dipoles constituting the capacitor. The new results corroborated the positive results of previous experiments and also indicate the validity of our theoretical forecast.

Actuation and dynamic mechanical characteristics of a core free flat dielectric electro-active polymer soft actuator

2020 ◽  
Vol 14 (4) ◽  
pp. 7396-7404
Author(s):  
Abdul Malek Abdul Wahab ◽  
Emiliano Rustighi ◽  
Zainudin A.
Keyword(s):  
Theoretical Model ◽  
Resonance Frequency ◽  
Dynamic Testing ◽  
Experimental Results ◽  
Percentage Error ◽  
Initial Tension ◽  
Average Percentage ◽  
Soft Actuator ◽  
Average Percentage Error ◽  
Mechanical Dynamics

Various complex shapes of dielectric electro-active polymer (DEAP) actuator have been promoted for several types of applications. In this study, the actuation and mechanical dynamics characteristics of a new core free flat DEAP soft actuator were investigated. This actuator was developed by Danfoss PolyPower. DC voltage of up to 2000 V was supplied for identifying the actuation characteristics of the actuator and compare with the existing formula. The operational frequency of the actuator was determined by dynamic testing. Then, the soft actuator has been modelled as a uniform bar rigidly fixed at one end and attached to mass at another end. Results from the theoretical model were compared with the experimental results. It was found that the deformation of the current actuator was quadratic proportional to the voltage supplied. It was found that experimental results and theory were not in good agreement for low and high voltage with average percentage error are 104% and 20.7%, respectively. The resonance frequency of the actuator was near 14 Hz. Mass of load added, inhomogeneity and initial tension significantly affected the resonance frequency of the soft actuator. The experimental results were consistent with the theoretical model at zero load. However, due to inhomogeneity, the frequency response function’s plot underlines a poor prediction where the theoretical calculation was far from experimental results as values of load increasing with the average percentage error 15.7%. Hence, it shows the proposed analytical procedure not suitable to provide accurate natural frequency for the DEAP soft actuator.

Design of Pipeline Composite Repairs: From Lab Scale Tests to FEA and Full Scale Testing

2014 ◽  
Author(s):  
Remy Her ◽  
Jacques Renard ◽  
Vincent Gaffard ◽  
Yves Favry ◽  
Paul Wiet
Keyword(s):  
Finite Element ◽  
Full Scale ◽  
Combined Loading ◽  
Material Strength ◽  
Repair System ◽  
Loading Conditions ◽  
Original Design ◽  
Composite Repair ◽  
Repair Systems ◽  
Composite Properties

Composite repair systems are used for many years to restore locally the pipe strength where it has been affected by damage such as wall thickness reduction due to corrosion, dent, lamination or cracks. Composite repair systems are commonly qualified, designed and installed according to ASME PCC2 code or ISO 24817 standard requirements. In both of these codes, the Maximum Allowable Working Pressure (MAWP) of the damaged section must be determined to design the composite repair. To do so, codes such as ASME B31G for example for corrosion, are used. The composite repair systems is designed to “bridge the gap” between the MAWP of the damaged pipe and the original design pressure. The main weakness of available approaches is their applicability to combined loading conditions and various types of defects. The objective of this work is to set-up a “universal” methodology to design the composite repair by finite element calculations with directly taking into consideration the loading conditions and the influence of the defect on pipe strength (whatever its geometry and type). First a program of mechanical tests is defined to allow determining all the composite properties necessary to run the finite elements calculations. It consists in compression and tensile tests in various directions to account for the composite anisotropy and of Arcan tests to determine steel to composite interface behaviors in tension and shear. In parallel, a full scale burst test is performed on a repaired pipe section where a local wall thinning is previously machined. For this test, the composite repair was designed according to ISO 24817. Then, a finite element model integrating damaged pipe and composite repair system is built. It allowed simulating the test, comparing the results with experiments and validating damage models implemented to capture the various possible types of failures. In addition, sensitivity analysis considering composite properties variations evidenced by experiments are run. The composite behavior considered in this study is not time dependent. No degradation of the composite material strength due to ageing is taking into account. The roadmap for the next steps of this work is to clearly identify the ageing mechanisms, to perform tests in relevant conditions and to introduce ageing effects in the design process (and in particular in the composite constitutive laws).

Pedestrian Detection Based on Histograms of Oriented Gradients in ROI

2012 ◽  
Vol 542-543 ◽  
pp. 937-940
Author(s):  
Ping Shu Ge ◽  
Guo Kai Xu ◽  
Xiu Chun Zhao ◽  
Peng Song ◽  
Lie Guo
Keyword(s):  
Traditional Method ◽  
Detection Method ◽  
Feature Vector ◽  
Pedestrian Detection ◽  
Region Of Interest ◽  
Experimental Results ◽  
Process Time ◽  
Vertical Edge ◽  
Histograms Of Oriented Gradients

To locate pedestrian faster and more accurately, a pedestrian detection method based on histograms of oriented gradients (HOG) in region of interest (ROI) is introduced. The features are extracted in the ROI where the pedestrian's legs may exist, which is helpful to decrease the dimension of feature vector and simplify the calculation. Then the vertical edge symmetry of pedestrian's legs is fused to confirm the detection. Experimental results indicate that this method can achieve an ideal accuracy with lower process time compared to traditional method.

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