A photoelastic-model study of stress distribution and rock fracture around mining excavations

1969 ◽  
Vol 9 (2) ◽  
pp. 75-81 ◽  
Author(s):  
Z. T. Bieniawski ◽  
C. P. G. Van Tonder
Keyword(s):  
Stress Distribution ◽  
Rock Fracture ◽  
Model Study ◽  
Photoelastic Model

scholarly journals Stress Analysis on Single Cobalt/Chrome Prosthesis With a 15-mm Cantilever Placed Over 10/13/15-mm–length Implants: A Simulated Photoelastic Model Study

2015 ◽  
Vol 41 (6) ◽  
pp. 706-711
Author(s):  
José Fábio Guastelli Gastaldo ◽  
Angélica Castro Pimentel ◽  
Maria Helena Gomes ◽  
Wilson Roberto Sendyk ◽  
Dalva Cruz Laganá
Keyword(s):  
Stress Distribution ◽  
Acrylic Resin ◽  
Photoelasticity Method ◽  
Metallic Prosthesis ◽  
Model Study ◽  
Photoelastic Model ◽  
Stress Levels ◽  
Reducing Stress ◽  
Implant Length ◽  
Cobalt Chrome

The aim of study was to assess the stress around 10/13/15-mm implants in the mandibular area with a 15-mm cantilevered acrylic-resin–coated prostheses following the application force, using the photoelasticity method. Three photoelastic mandibular models were created containing 10-, 13-, and 15-mm implants in length and 3.75 mm in diameter. The implants had bore internal hex connections and were placed parallel to the intermental region. Abutments with 1-mm high cuffs were placed over the implants, and a single cobalt/chrome metallic prosthesis with a 15-mm cantilever, coated with thermoplastic acrylic resin, was placed on top. Loads of 1.0 and 3.0 bars were applied, and the images were photographed and assessed by photoelasticity method. The greatest stress levels were observed for the 10-mm implants. The stress pattern was the same regardless of implant length; only the magnitude of the stress along the implant body revealed changes. Increased implant length played a role in reducing stress on the investigated area of the model, and the 15-mm implants exhibited the best performance in regard to stress distribution. The highest stress levels were found in the implants closest to the cantilever and the central implant. The longest implants were more favorable in regard to the stress distribution on the peri-implant support structures in the 15-mm cantilevered prosthesis under loads.

Influence of Implant-Retained Silicone Oculo-palpebral Prosthesis on Stress Distribution: A Pilot Study Using A Photoelastic Model

2015 ◽  
Vol 30 (6) ◽  
pp. 1303-1309
Author(s):  
Daniela Cortizo ◽  
Ricardo Kodama ◽  
Joaquim Oliveira ◽  
Alfredo Mesquita ◽  
Dalva Laganá ◽  
...  
Keyword(s):  
Pilot Study ◽  
Stress Distribution ◽  
Photoelastic Model

The analysis of elastic stress distribution in threaded tether connections

1987 ◽  
Vol 22 (4) ◽  
pp. 229-235 ◽  
Author(s):  
A Newport ◽  
D A Topp ◽  
G Glinka
Keyword(s):  
Finite Element Method ◽  
Stress Distribution ◽  
Load Distribution ◽  
Elastic Stress ◽  
Local Stress ◽  
The Finite Element Method ◽  
Photoelastic Model ◽  
Theoretical Predictions ◽  
Concentration Factors ◽  
Stress Concentration Factors

A technique is presented for predicting the load distribution and local stress distribution in threaded tether connections. The load distribution is derived by modelling the connection as a system of springs and beams. This distribution is then used in conjunction with the appropriate stress concentration factors derived by the finite element method to obtain the local stress distribution. A comparison is made between the theoretical predictions of local stress and published experimental results obtained from a photoelastic model.

scholarly journals Deviation Effect of Coaxiality on the Rock Brazilian Split

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Zenghui Zhao ◽  
Mingzhong Zhang ◽  
Qing Ma ◽  
Baosen Chen
Keyword(s):  
Tensile Strength ◽  
Numerical Calculation ◽  
Stress Distribution ◽  
Rock Fracture ◽  
Splitting Method ◽  
Maximum Tensile Stress ◽  
Analytic Solutions ◽  
Calculation Error ◽  
Splitting Test ◽  
Variable Function

Tension failure is one of the main forms of instability in geotechnical engineering. Aiming at the calculation error caused by the loading direction deviation of the Brazilian disc splitting method, a mechanical model of a disc under chord loading was constructed firstly. Based on the theory of complex variable function, the analytic solutions of stresses in a circular disc were deduced, and the calculation error of the tensile strength under chord loading was characterized by defining the error impact rate. And the stress distribution of a disc and the law of rock fracture under chord loading were detailed analyzed through numerical calculation. Through numerical calculation, the stress distribution of the disc and rock failure law under chordwise loading are discussed in detail. The results show that the stress concentration near the loading point is stronger under the chordwise loading comparing with the radial loading, which makes the disc more vulnerable to produce compression failure near the loading point. The disc exhibits a maximum tensile stress and a minimum compressive stress at the intersection of the loaded string and the horizontal diameter, so that tensile rupture damage is likely to occur here. With the increase of deviation angle, the tensile strength measured by the Brazilian splitting test decreases gradually, and the influence rate of error increases significantly. The proposed analytical solution under chord loading provides theoretical guiding significance for nonradial splitting failure of a disc.

Oblique incidence observations as an aid to three-dimensional stress separation

1966 ◽  
Vol 1 (4) ◽  
pp. 322-330 ◽  
Author(s):  
I M Allison
Keyword(s):  
Stress Distribution ◽  
Oblique Incidence ◽  
Three Dimensional ◽  
Optical Measurements ◽  
Complete Analysis ◽  
Stress Separation ◽  
Alternative Method ◽  
Photoelastic Model ◽  
Plate Girder

In the most general case the determination of the separate stresses along a selected line in a three-dimensional photoelastic model requires the evaluation of the shear slopes in two mutually perpendicular planes which intersect in the chosen line. The measurement of one normal and two oblique observations at a series of corresponding points in a set of parallel slices provides an alternative method for determining the shear slopes and yields a complete analysis of the stress distribution without further optical measurements. The method is illustrated by its use to analyse the stresses in a model of a loaded rail supported upon a deep welded plate girder.

scholarly journals Comparative photoelastic study of dental and skeletal anchorages in the canine retraction

2014 ◽  
Vol 19 (1) ◽  
pp. 100-105 ◽  
Author(s):  
Cristiane Aparecida de Assis Claro ◽  
Rosana Villela Chagas ◽  
Ana Christina Elias Claro Neves ◽  
Laís Regiane da Silva-Concílio
Keyword(s):  
Stress Distribution ◽  
Rubber Band ◽  
Cervical Region ◽  
Skeletal Anchorage ◽  
Distribution Analysis ◽  
Test Results ◽  
Second Molar ◽  
Canine Retraction ◽  
Photoelastic Model ◽  
Mandibular Canine

OBJECTIVE: To compare dental and skeletal anchorages in mandibular canine retraction by means of a stress distribution analysis. METHODS: A photoelastic model was produced from second molar to canine, without the first premolar, and mandibular canine retraction was simulated by a rubber band tied to two types of anchorage: dental anchorage, in the first molar attached to adjacent teeth, and skeletal anchorage with a hook simulating the mini-implant. The forces were applied 10 times and observed in a circular polariscope. The stresses located in the mandibular canine were recorded in 7 regions. The Mann-Whitney test was employed to compare the stress in each region and between both anchorage systems. The stresses in the mandibular canine periradicular regions were compared by the Kruskal-Wallis test. RESULTS: Stresses were similar in the cervical region and the middle third. In the apical third, the stresses associated with skeletal anchorage were higher than the stresses associated with dental anchorage. The results of the Kruskal-Wallis test showed that the highest stresses were identified in the cervical-distal, apical-distal, and apex regions with the use of dental anchorage, and in the apical-distal, apical-mesial, cervical-distal, and apex regions with the use of skeletal anchorage. CONCLUSIONS: The use of skeletal anchorage in canine retraction caused greater stress in the apical third than the use of dental anchorage, which indicates an intrusive component resulting from the direction of the force due to the position of the mini-implant and the bracket hook of the canine.

Sign in / Sign up

Export Citation Format

Share Document