Fracture Analysis of an Aluminum Alloy Gear Pump Housing

2016 ◽  
Vol 723 ◽  
pp. 288-293
Author(s):  
Ping Li ◽  
Yan Jie Zhao ◽  
Chun Qing Ma
Keyword(s):  
Visual Inspection ◽  
Optical Microscope ◽  
Gear Pump ◽  
Loading Capacity ◽  
Casting Defects ◽  
Exterior Surface ◽  
Initiation And Propagation ◽  
Pump Housing ◽  
Lower Material ◽  
Brittle Cleavage Fracture

The gear pump housing in bulldozer, which was made of cast Al-Si alloy, was found to break in two halves during running. In order to determine fracture reason of the gear pump housing failure analysis in detail were conducted by visual inspection, optical microscope and scanning electron microscope (SEM), chemical analysis, hardness inspection. Visual inspection showed that the crack source has a white semicircle on the interior side of the section and propagated toward the exterior surface of the housing with obvious radial state. Meanwhile, the inner wall has the wear trace in depth of 0.1 mm due to boring phenomenon. SEM observation indicated brittle cleavage fracture mechanism with many casting defects such as dendritic shrinkage and inclusion as well as initiated crack in gear pump housing. The casting defects probably promoted the initiation and propagation of the crack and decreased the loading capacity of the gear to impacting force from the inside shaft. The analysis results show that the failure of gear pump housing mainly resulted from serious boring phenomenon, dendritic shrinkage and the lower material performance.

Fatigue crack paths and properties in A356-T6 aluminum alloy microstructurally modified by friction stir processing under different conditions

2015 ◽  
Author(s):  
A. Tajiri ◽  
Y. Uematsu ◽  
T. Kakiuchi ◽  
Y. Suzuki
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Friction Stir Processing ◽  
Casting Defects ◽  
Processing Conditions ◽  
Tool Rotational Speed ◽  
Crack Initiation And Propagation ◽  
Friction Stir ◽  
Initiation And Propagation

A356-T6 cast aluminum alloy is a light weight structural material, but fatigue crack initiates and propagates from a casting defect leading to final fracture. Thus it is important to eliminate casting defects. In this study, friction stir processing (FSP) was applied to A356-T6, in which rotating tool with probe and shoulder was plunged into the material and travels along the longitudinal direction to induce severe plastic deformation, resulting in the modification of microstructure. Two different processing conditions with low and high tool rotational speeds were tried and subsequently fully reversed fatigue tests were performed to investigate the effect of processing conditions on the crack initiation and propagation behavior. The fatigue strengths were successfully improved by both conditions due to the elimination of casting defects. But the lower tool rotational speed could further improve fatigue strength than the higher speed. EBSD analyses revealed that the higher tool rotational speed resulted in the severer texture having detrimental effects on fatigue crack initiation and propagation resistances.

Study on Parameters Measurement System of Ball-End Cutter Based on Optical Vision Detection

2012 ◽  
Vol 538-541 ◽  
pp. 2109-2112
Author(s):  
Lin Zhi Liu
Keyword(s):  
Visual Inspection ◽  
Detection System ◽  
Ccd Camera ◽  
Optical Microscope ◽  
Least Square ◽  
Inspection System ◽  
Inspection Method ◽  
Optical Microscope Image ◽  
Parameters Measurement ◽  
Vision Detection

In manufacturing field, the geometric parameters measurement of tool is an essential process in manufacturing ball-end cutter. An optical visual inspection system of ball-end cutter parameters was studied through designing CCD camera, optical microscope, image grabbing card, visual light and 3D detection tables. Through the grabbing and processing image information of ball-end cutter, visual inspection method was applied to measure parameters of ball-end cutter. Some algorithms including the gray scale processing, median filtering, edge detection and least square fitting method of measured data were analyzed to develop image processing and tool detection software of ball-end cutter. The reliability and accuracy of this detection system were verified through the practical test.

scholarly journals Effect of Implantoplasty on Fatigue Performance and Surface Roughness of Narrow Diameter Dental Implants

2021 ◽  
Author(s):  
Octavi Camps-Font ◽  
Jorge Toledano-Serrabona ◽  
Ana Juiz-Camps ◽  
Rui Figueiredo ◽  
Cosme Gay-Escoda ◽  
...  
Keyword(s):  
Dental Implants ◽  
Visual Inspection ◽  
Bacterial Colonization ◽  
Testing Machine ◽  
Optical Microscope ◽  
Control Group ◽  
Scanning Electron Micrographs ◽  
Number Of Cycles ◽  
Type Of Failure ◽  
Scanning Electron

Abstract Implantoplasty (IP) is used in dental implants with peri-implantitis and aims to remove threads and polish rough surfaces in order to prevent bacterial colonization. As a result of this procedure, implant strength might be compromised. We tested 20 tapered screw-shaped Ti6Al4V dental implants with a simulated bone loss of 50%. Ten implants underwent IP and 10 served as controls. Surface topography (Sa, Sz, Ssk and Sdr) was analyzed with a confocal optical microscope. Subsequently, cyclic loads were applied with a servo-hydraulic mechanical testing machine (5x106 cycles at 15 Hz, between the maximal compression force - 529N in the IP group and 735N in the control group - and 10% of that force). We recorded the number of cycles until failure and the type of failure. Implant failure was analyzed by visual inspection and scanning electron microscopy. Implantoplasty reduced the median Sa from 1.76 (IQR=0.11) to 0.49 (IQR=0.16). The fatigue limits of the control and implantoplasty groups were 551 N and 529 N, respectively. The scanning electron micrographs showed fatigue striations indicating fatigue failure. The infinite life range of the dental implants evaluated was largely above the threshold of usual chewing forces. Implantoplasty seems to render a fairly smooth surface and has a limited impact upon fatigue resistance.

Fatigue Fracture of Turbine Blades: Case Studies

2013 ◽  
Vol 592-593 ◽  
pp. 712-715
Author(s):  
Marta Kianicová ◽  
Jaroslav Pokluda
Keyword(s):  
Case Studies ◽  
Fatigue Fracture ◽  
Fatigue Cracks ◽  
Turbine Blades ◽  
Rotor Blades ◽  
Casting Defects ◽  
Aircraft Engines ◽  
Testing Procedures ◽  
Fracture Surfaces ◽  
Initiation And Propagation

Fracture surfaces of two sets of rotor blades failed after strong testing procedures of aircraft engines in the test-stand are investigated by means of SEM. While the process of fatigue fracture in the first set of blades did not reveal any defect features, both the initiation and propagation of fatigue cracks was strongly influenced by casting defects.

scholarly journals The Influence of Gear Micropump Body Asymmetry On Stress Distribution

2017 ◽  
Vol 24 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Wacław Kollek ◽  
Piotr Osiński ◽  
Urszula Warzyńska
Keyword(s):  
Gear Pump ◽  
Stress Distributions ◽  
Hydraulic Systems ◽  
Pump Operation ◽  
Maximal Stress ◽  
Pump Housing ◽  
Calculation Results ◽  
Pumping Unit ◽  
Strength And Stiffness ◽  
Favorable Conditions

Abstract The paper presents the results of numerical calculations of stress distributions in the gear micropump body for applications in hydraulic systems, especially in the marine sector. The scope of the study was to determine the most favorable position of bushings and pumping unit in the gear pump body in terms of stress and displacement distribution in the pump housing. Fourteen cases of gear pump bushings and pumping unit locations were analyzed: starting from the symmetrical position relative to the central axis of the pump, up to a position shifted by 2.6 mm towards the suction channel of the pump. The analysis of the obtained calculation results has shown that the most favorable conditions for pump operation are met when the bushings are shifted by 2.2 mm towards the suction channel. In this case the maximal stress was equal to 109 MPa, while the highest displacement was about 15μm. Strength and stiffness criteria in the modernized pump body were satisfied.

Indentation Fatigue and In Situ Inspection of Damage Evolution for Glass

2010 ◽  
Vol 177 ◽  
pp. 451-454
Author(s):  
H.B. Zhou ◽  
Yi Wang Bao ◽  
Yan Qiu ◽  
Lan Chen ◽  
Xiu Fang Wang ◽  
...  
Keyword(s):  
Indentation Test ◽  
Crack Size ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Indentation Load ◽  
Cycle Number ◽  
Local Strength ◽  
Initiation And Propagation ◽  
Indentation Fatigue

Initiation and propagation of Hertz crack in glass was investigated by combining sphere indentation test and optical microscope under a transparent testing platform. Thus, the process of the crack growth in glass and the critical indentation load and contact crack radius could be determined conveniently. Indentation fatigue tests were carried out to understand the contact damage resistance, the fatigue cycle number for cracking increase with decrease of the fatigue load. This simple testing method is demonstrated convenient and available for calculating the surface local strength of glass in situ via measurements of the critical load and contact crack size.

Fatigue Failure Analysis on Key Components of Bladder Accumulators

2015 ◽  
Vol 750 ◽  
pp. 363-370
Author(s):  
Ya Ping Niu ◽  
Bing Bing Chen
Keyword(s):  
Failure Analysis ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Optical Microscope ◽  
Metallographic Analysis ◽  
The Finite Element Method ◽  
Valve Body ◽  
Support Ring ◽  
Initiation And Propagation

Fatigue failure analysis on key components of bladder accumulators was conducted. Failure fracture of the key components, which included the shell, the support ring and the oil inlet valve body in the accumulators, was investigated by optical microscope (OM) scanning electron microscope (SEM). According to the metallographic analysis and micro-hardness determination at the crack profile, crack initiation and propagation direction was confirmed. By simulation using the finite element method, it was detected that the peak stress of the key components applied on the contact surfaces. Obvious plastic deformation was observed at the region with high stress. However, the fatigue crack did not initiate at the contact surface, but occurred on the second high stress area without contact.

scholarly journals Device to evaluate cleanliness of fiber optic connectors using image processing and neural networks

2021 ◽  
Vol 11 (4) ◽  
pp. 3093
Author(s):  
Victor Fernandez ◽  
Javier Chavez ◽  
Guillermo Kemper
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Image Processing ◽  
Visual Inspection ◽  
Fiber Optic ◽  
Electronic Device ◽  
Digital Camera ◽  
Optical Microscope ◽  
Processing Algorithm ◽  
Image Processing Algorithm

This work proposes a portable, handheld electronic device, which measures the cleanliness in fiber optic connectors via digital image processing and artificial neural networks. Its purpose is to reduce the evaluation subjectivity in visual inspection done by human experts. Although devices with this purpose already exist, they tend to be cost-prohibitive and do not take advantage of neither image processing nor artificial intelligence to improve their results. The device consists of an optical microscope for fiber optic connector analysis, a digital camera adapter, a reduced-board computer, an image processing algorithm, a neural network algorithm and an LCD screen for equipment operation and results visualization. The image processing algorithm applies grayscale histogram equalization, Gaussian filtering, Canny filtering, Hough transform, region of interest segmentation and obtaining radiometric descriptors as inputs to the neural network. Validation consisted of comparing the results by the proposed device with those obtained by agreeing human experts via visual inspection. Results yield an average Cohen's Kappa of 0.926, which implies a very satisfactory performance by the proposed device.

High Temperature Corrosion of Fe-30Cr in Flowing CO2 Gas

2012 ◽  
Vol 501 ◽  
pp. 165-168
Author(s):  
S. Nurul Atikah ◽  
Norinsan Kamil Othman ◽  
Azman Jalar
Keyword(s):  
High Temperature ◽  
Visual Inspection ◽  
Optical Microscope ◽  
High Temperature Corrosion ◽  
Significant Weight Loss ◽  
X Ray Diffraction ◽  
Co2 Gas ◽  
X Ray ◽  
Change Measurement ◽  
Microstructure Observation

A plate of Fe-30Cr (wt%) were subjected to isothermal furnace at 600 °C in flowing CO2 gas at total pressure of approximately 1 atm. The reacted samples morphology and microstructure were characterized by using visual inspection, optical microscope, SEM and EDAX. The weight change measurement showed a fluctuating result during the exposure. The significant weight loss was observed after five hours exposure due to oxide scale exfoliation. Formation of different oxide and element presents on the interface of the specimen such as Cr2O3, C and Fe3C were revealed by X-ray diffraction and with supported by EDAX analysis. This behavior of the high temperature corrosion on Fe-30Cr was discussed based on morphology and microstructure observation.

Fatigue Microcrack Initiation and Propagation of Aluminum Alloy under Different Stress Level and Stress Ratio

2011 ◽  
Vol 239-242 ◽  
pp. 1495-1500
Author(s):  
Gui Xue Bian ◽  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Yong Zhang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Stress Level ◽  
Stress Ratio ◽  
High Stress ◽  
Optical Microscope ◽  
Initiation And Propagation ◽  
Microcrack Initiation ◽  
Stress Ratios ◽  
High Stress Level

The microstructure of fatigue fracture of aluminum alloys under various stresses and stress ratios were studied by optical microscope and scanning electron microscope, and the influences of microstructure features on microcrack initiation and propagation were investigated. The results show that the fatigue microcrack originated from surface or subsurface of specimens. And with the increase of stress ratio, fatigue crack originated from deeper subsurface at the same stress level. With the increase of stress level, fatigue crack originated from shallower subsurface or surface at same stress ratio. There is an increase in crack propagation region as the stress level decreases at the same stress ratio. Increasing of stress ratio, increases crack propagation region under same stress level. Microcrack generally originated from secondary (S phase particles) and larger particles at low stress level and high stress ratio. Microcrack generally originated from larger constituent particles at high stress level and low stress ratio. Microcracks propagation is evidently impeded by grain boundaries at low stress level and high stress ratio.

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