Fracture mechanical analysis of cracks in polymer encapsulated metal structures

2002 ◽  
Author(s):  
O. Wittler ◽  
P. Sprafke ◽  
J. Auersperg ◽  
B. Michel ◽  
H. Reichl
Keyword(s):  
Mechanical Analysis ◽  
Metal Structures

Composite repair of sub-sea pipelines

2011 ◽  
Vol 51 (2) ◽  
pp. 729
Author(s):  
Colin Wood ◽  
Karen Kozielski ◽  
Wendy Tian ◽  
Song Gao ◽  
Jonathan Hodgkin ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Prolonged Exposure ◽  
Mechanical Test ◽  
Extended Period ◽  
Mechanical Analysis ◽  
Test Results ◽  
Metal Structures ◽  
Oil And Gas Fields ◽  
Gas Fields ◽  
Safety And Environment

The development of new deepwater oil and gas fields provide an opportunity for increased use of new materials. Conventional infrastructure is constructed using significant quantities of steel and concrete, which is becoming less practical in comparison to new light weight, easy to handle composites. When infrastructure needs to be repaired, there is often a requirement for underwater welding, which carries considerable occupational health, safety and environment (OHSE) risks. For this reason, moving away from traditional metal structures or repair technologies is increasingly attractive. In recent years a number of new water activated composite wrap materials have been developed for use in underwater applications. The materials properties that are required can be difficult to achieve and maintain over an extended period of exposure to the marine environment, though, so many research groups are working on this challenge. A comprehensive literature review has been undertaken to identify present state of the art ideas for the development of improved underwater materials and this will be discussed in the context of adhesive applications. Preliminary material characterisation work will be described where new resins have been formulated to perform well in marine environments and survive prolonged exposure to seawater. Experiments were carried out in artificial seawater and samples left to cure at a range of temperatures DSC and dynamic mechanical analysis (DMTA) were used to evaluate the crosslink density of the network and the glass transition temperature respectively, while FTIR was used to determine the chemical structure in the cured systems. Preliminary mechanical test results have shown significant improvement in strength for the new formulations compared to a set of control samples of commercially available materials.

Light-cured dental composites characterization by Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 428-429
Author(s):  
B. M. Culbertson ◽  
M. L. Devinev ◽  
E. C. Kao
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Service Performance ◽  
Dental Composite ◽  
Dental Composites ◽  
Neat Resin ◽  
Scanning Calorimetry ◽  
Research Meeting ◽  
Formulation Variables

The service performance of current dental composite materials, such as anterior and posterior restoratives and/or veneer cements, needs to be improved. As part of a comprehensive effort to find ways to improve such materials, we have launched a broad spectrum study of the physicochemical and mechanical properties of photopolymerizable or visible light cured (VLC) dental composites. The commercially available VLC materials being studied are shown in Table 1. A generic or neat resin VLC system is also being characterized by SEM and TEM, to more fully understand formulation variables and their effects on properties.At a recent dental research meeting, we reported on the differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) characterization of the materials in Table 1. It was shown by DSC and DMA that the materials are substantially undercured by commonly used VLC techniques. Post curing in an oral cavity or a dry environment at 37 to 50°C for 7 or more hours substantially enhances the cure of the materials.

Rubber–Road Contact: Comparison of Physics-Based Theory and Indoor Experiments

2016 ◽  
Vol 44 (3) ◽  
pp. 150-173 ◽  
Author(s):  
Mehran Motamedi ◽  
Saied Taheri ◽  
Corina Sandu
Keyword(s):  
Rough Surface ◽  
Practical Importance ◽  
Surface Profile ◽  
Surface Characteristics ◽  
Mechanical Analysis ◽  
Friction Model ◽  
Rubber Friction ◽  
Optical Profilometer ◽  
Viscoelastic Modulus ◽  
Longitudinal Slip

ABSTRACT For tire designers, rubber friction is a topic of pronounced practical importance. Thus, development of a rubber–road contact model is of great interest. In this research, to predict the effectiveness of the tread compound in a tire as it interacts with the pavement, the physics-based multiscale rubber-friction theories developed by B. Persson and M. Klüppel were studied. The strengths of each method were identified and incorporated into a consolidated model that is more comprehensive and proficient than any single, existing, physics-based approach. In the present work, the friction coefficient was estimated for a summer tire tread compound sliding on sandpaper. The inputs to the model were the fractal properties of the rough surface and the dynamic viscoelastic modulus of rubber. The sandpaper-surface profile was measured accurately using an optical profilometer. Two-dimensional parameterization was performed using one-dimensional profile measurements. The tire tread compound was characterized via dynamic mechanical analysis. To validate the friction model, a laboratory-based, rubber-friction test that could measure the friction between a rubber sample and any arbitrary rough surface was designed and built. The apparatus consisted of a turntable, which can have the surface characteristics of choice, and a rubber wheel in contact with the turntable. The wheel speed, as well as the turntable speed, could be controlled precisely to generate the arbitrary values of longitudinal slip at which the dynamic coefficient of friction was measured. The correlation between the simulation and the experimental results was investigated.

STOCHASTIC CALCULATION OF LIFETIME PREDICTION FOR COMPONENTS IN METAL STRUCTURES DUE TO THE GROWTH OF MICRODEFECTS

2020 ◽  
Vol 4 (97) ◽  
pp. 69-76
Author(s):  
IGOR N. SILVERSTOV
Keyword(s):  
Fatigue Strength ◽  
Fracture Mechanics ◽  
Stochastic Approach ◽  
Fatigue Curve ◽  
Probability Of Failure ◽  
Lifetime Prediction ◽  
Statistical Distributions ◽  
Metal Structures

A stochastic approach has been developed to evaluate fatigue strength using elements of the fracture mechanics. The article presents a method for determining the initial parameters of statistical distributions. It also considers the method for constructing a fatigue curve for a component of any size and configuration with any given probability of failure.

MECHANICAL ANALYSIS OF THE ADAPTATIVE HIP GUIDE FOR PERIACETABULAR OSTEOTOMY SURGERY

2017 ◽  
Author(s):  
Flavia Bastos ◽  
ALEXANDRE SCARI ◽  
BRUNO GONCALVES SCHRODER e SOUZA ◽  
Fabiane Grazielle Silva
Keyword(s):  
Periacetabular Osteotomy ◽  
Mechanical Analysis

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

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