scholarly journals Fractal‐based dynamic response of a pair of spur gears considering microscopic surface morphology

2021 ◽  
Vol 1 (2) ◽  
pp. 194-206
Author(s):  
Xin Yu ◽  
Yunyun Sun ◽  
Sheng Liu ◽  
Shijing Wu
Keyword(s):  
Surface Morphology ◽  
Dynamic Response ◽  
Spur Gears ◽  
Microscopic Surface

An Analytical Study of the Effect of the Contact Ratio on the Spur Gear Dynamic Response

1999 ◽  
Vol 122 (4) ◽  
pp. 508-514 ◽  
Author(s):  
Anette Andersson
Keyword(s):  
Dynamic Response ◽  
Transmission Error ◽  
Spur Gear ◽  
Spur Gears ◽  
Contact Ratio ◽  
Constant Stiffness ◽  
Gear Mesh ◽  
Critical Rotational Speed ◽  
Stiffness Variation ◽  
Gear Mesh Stiffness

A model was used, where the total gear mesh stiffness was approximated by two constant stiffness levels, in order to analyze the influence of the contact ratio on the dynamic response of spur gears. Due to the stiffness variation there is parametric excitation of the transmission error, which generally causes tooth separation at certain critical rotational speeds. The present paper discloses a method to analytically calculate which contact ratio to use in order to avoid tooth separation near a specific critical rotational speed. [S1050-0472(00)02604-0]

Novel tooth modification methodology for multistage spur gears considering dynamic deformation of housing

2019 ◽  
Vol 233 (21-22) ◽  
pp. 7257-7269
Author(s):  
Hanjie Jia ◽  
Datong Qin ◽  
Changzhao Liu
Keyword(s):  
Dynamic Response ◽  
Dynamic Simulation ◽  
High Performance ◽  
System Dynamic ◽  
Dynamic Factor ◽  
Spur Gears ◽  
The Finite Element Method ◽  
Driving System ◽  
Profile Modification ◽  
Tooth Modification

Tooth modification is critical when designing high-performance gear transmission systems. However, it is difficult to accurately calculate the system deformation and tooth modification amount using the traditional empirical formula. Although the finite element method provides accurate results, it is time consuming and its direct application to tooth modification for multistage geared systems is difficult. This study proposes a novel methodology to define tooth modification in both width and profile directions, which can be used for multistage spur gears. First, a housing-transmission coupled dynamic model is built, and the actual meshing state of each gear pair is obtained from dynamic simulation. Lead and profile modification are then conducted sequentially using the actual meshing state as an input. As the optimal tooth modification parameter is determined by the system dynamic response, and the tooth modification in turn influences the system dynamic response, the “dynamic simulation” and “tooth modification” are repeated iteratively until the modification parameter converges. Taking the drum driving system of a shearer as an example, the optimal tooth modification parameter is obtained after three iterations, and the dynamic factor and maximum tooth contact stress clearly decreased after applying the optimal tooth modification.

Impact of Tooth Indexing Errors on Dynamic Factors of Spur Gears: Experiments and Model Simulations

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
D. Talbot ◽  
A. Sun ◽  
A. Kahraman
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Load Distribution ◽  
Distribution Model ◽  
Spur Gears ◽  
Strain Measurements ◽  
Model Simulations ◽  
Dynamic Factors ◽  
Error Dynamic

This paper investigates the influences of tooth indexing errors on dynamic factors of spur gears. An experimental study is performed using root strain measurements to (i) establish baseline dynamic behavior of gears having negligible indexing errors and (ii) characterize changes caused by tightly controlled intentional indexing errors to this baseline dynamic behavior. For this, test gears having different forms of indexing errors are paired with an instrumented gear having negligible indexing error. Dynamic root strains of teeth in the neighborhood of teeth with indexing error are measured. A dynamic gear load distribution model is employed to simulate these experiments. Both measurements and predictions indicate clearly that the baseline dynamic response, dominated by well-defined resonance peaks, is altered significantly by transient vibrations induced by indexing errors, in the process increasing dynamic factors significantly in comparison to the case of negligible indexing error.

Sem Examinations of Glass Knives

1970 ◽  
Vol 28 ◽  
pp. 282-283
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Tensile Loading ◽  
Resultant Force ◽  
Stress Concentrations ◽  
Edge Chipping ◽  
Surface Flaws ◽  
Edge Defects ◽  
Microscopic Surface

There are two types of edge defects common to glass knives as typically prepared for microtomy purposes: 1) striations and 2) edge chipping. The former is a function of the free breaking process while edge chipping results from usage or bumping of the edge. Because glass has no well defined planes in its structure, it should be highly resistant to plastic deformation of any sort, including tensile loading. In practice, prevention of microscopic surface flaws is impossible. The surface flaws produce stress concentrations so that tensile strengths in glass are typically 10-20 kpsi and vary only slightly with composition. If glass can be kept in compression, wherein failure is literally unknown (1), it will remain intact for long periods of time. Forces acting on the tool in microtomy produce a resultant force that acts to keep the edge in compression.

An Established Epithelial Cell Line (NPC/HK1) from a Nasopharyngeal Carcinoma - II. A Sem Study

1982 ◽  
Vol 40 ◽  
pp. 224-225
Author(s):  
Li C.L. ◽  
Chew E.C. ◽  
Huang D.P. ◽  
Ho H.C. ◽  
Mak L.S. ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Epithelial Cell ◽  
Surface Morphology ◽  
Cell Line ◽  
Epithelial Cell Line ◽  
Present Communication ◽  
Cells In Culture ◽  
Sem Study ◽  
Well Differentiated

An epithelial cell line, NPC/HK1, has recently been successfully established from a nasopharyngeal carcinoma of the moderately to well differentiated squamous type. The present communication reports on the surface morphology of the NPC/HK1 cells in culture.

Specimen Collection Effect in Scanning Electron Microscopy Images

1972 ◽  
Vol 30 ◽  
pp. 448-449
Author(s):  
J. Temple Black ◽  
Jose Guerrero
Keyword(s):  
Surface Morphology ◽  
Secondary Electron Emission ◽  
Secondary Electrons ◽  
Charge Effects ◽  
Material Density ◽  
Specimen Collection ◽  
The Subject ◽  
Curved Paths ◽  
Subject Material ◽  
Microscopy Images

In the SEM, contrast in the image is the result of variations in the volume secondary electron emission and backscatter emission which reaches the detector and serves to intensity modulate the signal for the CRT's. This emission is a function of the accelerating potential, material density, chemistry, crystallography, local charge effects, surface morphology and especially the angle of the incident electron beam with the particular surface site. Aside from the influence of object inclination, the surface morphology is the most important feature In producing contrast. “Specimen collection“ is the name given the shielding of the collector by adjacent parts of the specimen, producing much image contrast. This type of contrast can occur for both secondary and backscatter electrons even though the secondary electrons take curved paths to the detector-collector.Figure 1 demonstrates, in a unique and striking fashion, the specimen collection effect. The subject material here is Armco Iron, 99.85% purity, which was spark machined.

The Effect of Benzene on Bluegill Olfactory Lamellae

1985 ◽  
Vol 43 ◽  
pp. 574-575
Author(s):  
D.R. Mattie ◽  
J.W. Fisher
Keyword(s):  
Surface Morphology ◽  
Soluble Fraction ◽  
Lepomis Macrochirus ◽  
Sublethal Concentration ◽  
Water Soluble ◽  
Major Constituent ◽  
Jet Fuels ◽  
Aquatic Biota ◽  
Normal Surface ◽  
Cacodylate Buffer

Jet fuels such as JP-4 can be introduced into the environment and come in contact with aquatic biota in several ways. Studies in this laboratory have demonstrated JP-4 toxicity to fish. Benzene is the major constituent of the water soluble fraction of JP-4. The normal surface morphology of bluegill olfactory lamellae was examined in conjunction with electrophysiology experiments. There was no information regarding the ultrastructural and physiological responses of the olfactory epithelium of bluegills to acute benzene exposure.The purpose of this investigation was to determine the effects of benzene on the surface morphology of the nasal rosettes of the bluegill sunfish (Lepomis macrochirus). Bluegills were exposed to a sublethal concentration of 7.7±0.2ppm (+S.E.M.) benzene for five, ten or fourteen days. Nasal rosettes were fixed in 2.5% glutaraldehyde and 2.0% paraformaldehyde in 0.1M cacodylate buffer (pH 7.4) containing 1.25mM calcium chloride. Specimens were processed for scanning electron microscopy.

Observation of surface morphology by reflection electron holography

1989 ◽  
Vol 47 ◽  
pp. 536-537
Author(s):  
N. Osakabe ◽  
J. Endo ◽  
T. Matsuda ◽  
A. Tonomura
Keyword(s):  
Phase Shift ◽  
Surface Morphology ◽  
High Sensitivity ◽  
High Energy ◽  
Path Difference ◽  
Transmission Mode ◽  
Electron Holography ◽  
Dynamical Process ◽  
High Vertical Resolution ◽  
Amplification Technique

Progress in microscopy such as STM and TEM-TED has revealed surface structures in atomic dimension. REM has been used for the observation of surface dynamical process and surface morphology. Recently developed reflection electron holography, which employes REM optics to measure the phase shift of reflected electron, has been proved to be effective for the observation of surface morphology in high vertical resolution ≃ 0.01 Å.The key to the high sensitivity of the method is best shown by comparing the phase shift generation by surface topography with that in transmission mode. Difference in refractive index between vacuum and material Vo/2E≃10-4 owes the phase shift in transmission mode as shownn Fig. 1( a). While geometrical path difference is created in reflection mode( Fig. 1(b) ), which is measured interferometrically using high energy electron beam of wavelength ≃0.01 Å. Together with the phase amplification technique , the vertivcal resolution is expected to be ≤0.01 Å in an ideal case.

Sign in / Sign up

Export Citation Format

Share Document