Thrust Force Modeling of the Flagella-Like Swimming Micro-Robot

2013 ◽  
Vol 461 ◽  
pp. 930-941
Author(s):  
Ling Wang ◽  
Bai Chen ◽  
Peng Wang ◽  
Sun Chen ◽  
Qian Yun Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Thrust Force ◽  
Rectangular Cross Section ◽  
Helix Angle ◽  
Simulation Data ◽  
Force Modeling ◽  
Macro Scale ◽  
Micro Robot ◽  
Resistive Force Theory

In this paper, helix tails with rectangular cross-section were designed for propelling a kind of flagella-like swimming robot. CFD (Computational Fluid Dynamics) software was applied to analyze the major influencing factors of the robots mechanical properties. It is revealed that the thrust reaches the maximum when the helix tails cross-section width is 0.36 times the diameter. Meanwhile, the helix tails should be designed according to the requirements with the largest diameter, close to but less than 45° helix angle and multi-turns under the limitation of the workspace. Combining these simulation data with the derivation process of Resistive Force Theory, the models for the mechanical properties simulation of the swimming robot were revised, and the explicit empirical formula of propulsive force is obtained. This model lays a good foundation for the robots motion control as well as unified mathematical description for macro-scale and micro-scale robots.

Recommendations for Designing Wooden Arches on Metal-toothed Plates

2021 ◽  
Author(s):  
Bohdan Demchyna ◽  
◽  
Yaroslav Shydlovskyi
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Laboratory Testing ◽  
Horizontal Plane ◽  
Thrust Force ◽  
Rectangular Cross Section ◽  
Rectangular Section ◽  
Pilot Studies ◽  
Different Types ◽  
The Stability

This paper presents the findings of the pilot studies and recommendations for designing of two-hinged wooden arches. The prototype models of wooden arches with the span of 6mand the rise of 1m were designed. The models had a rectangular cross-section of 180x40mm and a T-section of 180x40mm with a plywood plate with the thickness of 6 mm and the width of 500mm. The main objective of the T-section was to ensure the stability of the arch. Each arch was composed of six segments –boards joined by clamping plates. The bowstring truss including two inclined tie bars enables carrying asymmetric loads and provides in-plane stability of the arch. A methodology for laboratory testing of the prototype models of wooden arches subjected to different types of loads was developed. Two prototypes of wooden arches were tested with rectangular cross-sections and two T-section ones subjected to the loading across the span, and two prototypes subjected to the half-span loading. In total, eight arches were tested. Deflections of arches, cross-section deformations and arch thrust force were recorded. The arches were tested until failure. The results of testing revealed insufficient stability of the arches with rectangular cross-section in the horizontal plane. For the arches with T-section the whole arch rib was damaged, the in-plane stability was ensured by the T-section. The collapsing force of the T-section arch was about 1.3 times greater than the collapsing force of the rectangular section arches.

A Comparative Study of the Properties of Bandage-form Splinting Materials

1982 ◽  
Vol 11 (3) ◽  
pp. 125-134 ◽  
Author(s):  
J M Gill ◽  
P Bowker
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Weight Ratio ◽  
Physical And Mechanical Properties ◽  
Strength Development ◽  
X Ray ◽  
Three Point Bending ◽  
Plaster Of Paris ◽  
X Ray Absorption

The physical and mechanical properties of three new bandage-form splinting materials (Baycast, Crystona and Hexcelite) have been compared with those of plaster of Paris. Properties evaluated including working strength, rate of strength development, elastic modulus, exothermic heat and X-ray absorption coefficient. All mechanical testing was carried out on rectangular cross-section specimens in three-point bending. Whilst the three newer materials differed widely they all showed some advantages over plaster of Paris although none could be definitely stated as being superior in all respects. As regards mechanical properties, Baycast was found to be significantly stronger than the other materials and to have a higher strength to weight ratio. The difficulties in formulating laboratory tests which are clinically relevant are discussed and the need to consider other factors, such as ease of application and advantages to the patient, is emphasized.

scholarly journals The study of the mechanical properties of the porous gypsum

2015 ◽  
Vol 14 (4) ◽  
pp. 043-054
Author(s):  
Jakub Gontarz ◽  
Jerzy Podgórski
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Property Values ◽  
Bending Test ◽  
Test Results ◽  
Three Point Bending ◽  
Laboratory Test Results ◽  
Section Sample

The paper presents the laboratory test results of the mechanical properties of porous gypsum. Material for the study was obtained from gypsum Pro-Monta plate of 100mm thick. Based on the compression test of cubic samples, following mechanical properties were determined: compressive strength, Poisson's ratio and Young's modulus. Tensile strength was determined based on three-point bending test of rectangular cross section sample. Also a friction coefficients were investigated as follows: between the smoothed surface of the sample and a fiberboard pad, between a rough surfaces (after cutting) and fiberboard pad. A porosity of the material samples was determined using standard method. The material’s mechanical property values can be useful for modeling destruction and deformation of a porous gypsum undertaken by analytical and numerical methods.

scholarly journals Designing for People’s Safety on Flooded Streets: Uncertainties and the Influence of the Cross-Section Shape, Roughness and Slopes on Hazard Criteria

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2119
Author(s):  
Luís Mesquita David ◽  
Rita Fernandes de Carvalho
Keyword(s):  
Cross Section ◽  
Overland Flow ◽  
Rectangular Cross Section ◽  
Safety Hazard ◽  
Cross Section Shape ◽  
Section Shape ◽  
Flood Flows ◽  
The Cross ◽  
Flooding Risk

Designing for exceedance events consists in designing a continuous route for overland flow to deal with flows exceeding the sewer system’s capacity and to mitigate flooding risk. A review is carried out here on flood safety/hazard criteria, which generally establish thresholds for the water depth and flood velocity, or a relationship between them. The effects of the cross-section shape, roughness and slope of streets in meeting the criteria are evaluated based on equations, graphical results and one case study. An expedited method for the verification of safety criteria based solely on flow is presented, saving efforts in detailing models and increasing confidence in the results from simplified models. The method is valid for 0.1 m2/s 0.5 m2/s. The results showed that a street with a 1.8% slope, 75 m1/3s−1 and a rectangular cross-section complies with the threshold 0.3 m2/s for twice the flow of a street with the same width but with a conventional cross-section shape. The flow will be four times greater for a 15% street slope. The results also highlighted that the flood flows can vary significantly along the streets depending on the sewers’ roughness and the flow transfers between the major and minor systems, such that the effort detailing a street’s cross-section must be balanced with all of the other sources of uncertainty.

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