Strength testing of dental stone: A comparison of compressive, tensile, transverse, and shear strength tests

1983 ◽  
Vol 17 (2) ◽  
pp. 293-299 ◽  
Author(s):  
J. A. von Fraunhofer ◽  
R. R. Spiers
Keyword(s):  
Shear Strength ◽  
Strength Testing ◽  
Strength Tests

scholarly journals EARLY STRENGTH TESTING AFTER ACL RECONSTRUCTION IMPACTS ISOKINETIC STRENGTH PERFORMANCE AT TIME OF RETURN TO SPORT

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0011
Author(s):  
Adam Weaver ◽  
Dylan Roman ◽  
Maua Mosha ◽  
Nicholas Giampetruzzi
Keyword(s):  
Test Performance ◽  
Knee Extension ◽  
Strength Test ◽  
Strength Testing ◽  
Isokinetic Strength ◽  
Rehabilitation Process ◽  
Strength Performance ◽  
Knee Extension Strength ◽  
Isometric Knee Extension ◽  
Strength Tests

Background: The standard of care in ACL reconstruction (ACLR) typically involves standardized strength testing at 6 months or later to assess a patient’s readiness to return to play (RTP) using isokinetic and isometric testing, and functional strength testing. Recent literature suggests that isokinetic knee extension strength should demonstrate 89% limb symmetry index (LSI) or greater prior to returning to sport. However, there is little known on the effects of strength testing early in the rehabilitation process and the relationship to strength test performance at time of RTP. Purpose: The purpose of this study was to examine how early post-operative strength test performance impacts isokinetic strength outcomes at RTP testing in adolescents. Methods: The retrospective cohort study included patients undergoing primary ACLR between 12 and 18 years of age, early post-operative strength measures, and isokinetic dynamometer strength at RTP from July 2017 and April 2019. Data was dichotomized into desired outcomes at 3 months: >70% isometric knee extension LSI, > 20 repetitions on anterior stepdown test (AST), > 90% LSI Y Balance. At RTP testing, isokinetic knee extension strength data was categorized into >89% LSI at 3 speeds (300, 180, 60°/sec). Chi square testing and odds ratio statistics were used to examine association and its magnitude. Results: 63 patients met inclusion criteria (38 females; 15.37±1.66 years old). >70% LSI isometric knee extension strength at 3 months showed a significant association (Table 2) and demonstrated the strongest odds of having >89% LSI on isokinetic strength tests at all 3 speeds at RTP with 180°/sec being the highest (OR=14.5; 95% CI=4.25,49.43; p= <0.001). Performance on AST showed a significant association (χ2 (1, n=63) = 17.00, p <0.001), and highest odds at 180°/sec (OR=4.61; 95% CI = 1.59, 13.39, p=<0.001) and 60°/sec (OR= 3.07; 95% CI = 1.10, 8.63, p= 0.04). Combination of performance on isometric strength tests and AST showed a significant association to isokinetic strength at all three speeds, but less predictive then isometrics in isolation. (Table 2). There was no significant relationship between YBR LSI at 3 months and isokinetic strength at 6 months. Conclusion: Standardized strength testing early in rehabilitation can help identify patients that will successfully complete RTP testing. Our results suggest that isometric knee extension strength and timed anterior stepdown test provide meaningful clinical information early in the rehabilitation process. This data also suggests that the use of YBAL for predicting isokinetic strength performance is limited. [Table: see text][Table: see text]

scholarly journals An Experimental Study on a Composite Bonding Structure for Steel Bridge Deck Pavements

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xiaoguang Zheng ◽  
Qi Ren ◽  
Huan Xiong ◽  
Xiaoming Song
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Epoxy Resin ◽  
Bonding Strength ◽  
Bridge Deck ◽  
Steel Bridge ◽  
Shear Tests ◽  
Bonding Structure ◽  
Asphalt Overlay ◽  
Strength Tests

As one of the major contributors to the early failures of steel bridge deck pavements, the bonding between steel and asphalt overlay has long been a troublesome issue. In this paper, a novel composite bonding structure was introduced consisting of epoxy resin micaceous iron oxide (EMIO) primer, solvent-free epoxy resin waterproof layer, and ethylene-vinyl acetate (EVA) hot melt pellets. A series of strength tests were performed to study its mechanical properties, including pull-off strength tests, dumbbell tensile tests, lap shear tests, direct tension tests, and 45°-inclined shear tests. The results suggested that the bonding structure exhibited fair bonding strength, tensile strength, and shear strength. Anisotropic behaviour was also observed at high temperatures. For epoxy resin waterproof layer, the loss of bonding strength, tensile strength, and shear strength at 60°C was 70%, 35%, and 39%, respectively. Subsequent pavement performance-oriented tests included five-point bending tests and accelerated wheel tracking tests. The impacts of bonding on fatigue resistance and rutting propagation were studied. It was found that the proposed bonding structure could provide a durable and well-bonded interface and was thus beneficial to prolong the fatigue lives of asphalt overlay. The choice of bonding materials was found irrelevant to the ultimate rutting depth of pavements. But the bonding combination of epoxy resin waterproof and EVA pellets could delay the early-stage rutting propagation.

scholarly journals Strength Tests and Numerical Simulations of Loess Modified by Desulfurization Ash and Fly Ash

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 512
Author(s):  
Zhi Cheng ◽  
Xinrong Cheng ◽  
Yuchao Xie ◽  
Zhe Ma ◽  
Yuhao Liu
Keyword(s):  
Shear Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Utilization Rate ◽  
Direct Shear ◽  
Test Results ◽  
Mass Ratio ◽  
Direct Shear Tests ◽  
Strength Tests ◽  
Actual Test

Desulfurization ash and fly ash are solid wastes discharged from boilers of power plants. Their utilization rate is low, especially desulfurization ash, most of which is stored. In order to realize their resource utilization, they are used to modify loess in this paper. Nine group compaction tests and 32 group direct shear tests are done in order to explore the influence law of desulfurization ash and fly ash on the strength of the loess. Meanwhile, FLAC3D software is used to numerically simulate the direct shear test, and the simulation results and the test results are compared and analyzed. The results show that, with the increase of desulfurization ash’s amount, the shear strength of the modified loess increases first and then decreases. The loess modified by the fly ash has the same law with that of the desulfurization ash. The best mass ratio of modified loess is 80:20. When the mass ratio is 80:20, the shear strength of loess modified by the desulfurization ash is 12.74% higher than that of the pure loess on average and the shear strength of loess modified by fly ash is 3.59% higher than that of the pure loess on average. The effect of the desulfurization ash on modifying the loess is better than that of the fly ash. When the mass ratio is 80:20, the shear strength of loess modified by the desulfurization ash is 9.15% higher than that of the fly ash on average. Comparing the results of the simulation calculation with the actual test results, the increase rate of the shear stress of the FLAC3D simulation is larger than that of the actual test, and the simulated shear strength is about 8.21% higher than the test shear strength.

scholarly journals Bonding of plywood 

2016 ◽  
Vol 62 (No. 4) ◽  
pp. 198-204
Author(s):  
M. Brožek
Keyword(s):  
Tensile Strength ◽  
Testing Machine ◽  
Strength Testing ◽  
Bonded Joints ◽  
Rupture Force ◽  
Oblique Direction ◽  
Direction Angle ◽  
Economical Evaluation ◽  
Wood Bonding ◽  
Strength Tests

The contribution contains results of bonded joints strength tests. The tests were carried out according to the modified standard ČSN EN 1465 (66 8510):2009. The spruce three-ply wood of 4 mm thickness was used for bonding according to ČSN EN 636 (49 2419):2013. The test samples of 100 × 25 mm size were cut out from a semi-product of 2,440 × 1,220 mm size in the direction of its longer side (angle 0°), in the oblique direction (angle 45°) and in the direction of its shorter side (crosswise – angle 90°). The bonding was carried out using eight different domestic as well as foreign adhesives according to the technology prescribed by the producer. All used adhesives were designated for wood bonding. At the bonding the consumption of the adhesive was determined. After curing, the bonded assemblies were loaded using a universal tensile-strength testing machine up to the rupture. The rupture force and the rupture type were registered. Finally, the technical-economical evaluation of the experiments was carried out. 

Modelling in situ shear strength testing of asphalt concrete pavements using the finite element method

2001 ◽  
Vol 28 (3) ◽  
pp. 541-544 ◽  
Author(s):  
Wael Bekheet ◽  
Yasser Hassan ◽  
AO Abd El Halim
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Traffic Safety ◽  
Asphalt Concrete ◽  
Material Properties ◽  
Fundamental Property ◽  
Analytical Models ◽  
Strength Testing ◽  
Concrete Pavements

Rutting is one of the well-recognized road surface distresses in asphalt concrete pavements that can affect the pavement service life and traffic safety. Previous studies have shown that the shear strength of asphalt concrete pavements is a fundamental property in resisting rutting. Laboratory investigation has shown that improving the shear strength of the asphalt concrete mix can reduce surface rutting by more than 30%, and the SUPERPAVE mix design method has acknowledged the importance of the shear resistance of asphalt mixes as a fundamental property in resisting deformation of the pavement. An in situ shear strength testing facility was developed at Carleton University, and a more advanced version of this facility is currently under development in cooperation with the Transportation Research Board and the Ontario Ministry of Transportation. In using this facility, a circular area of the pavement surface is forced to rotate about a normal axis by applying a torque on a circular plate bonded to the surface. The pavement shear strength is then related to the maximum torque. This problem has been solved mathematically in the literature for a linear, homogeneous, and isotropic material. However, the models for other material properties are mathematically complicated and are not applicable to all cases of material properties. Therefore, developing a model that can accurately analyze the behaviour of asphalt concrete pavements during the in situ shear test has proven pivotal. This paper presents the development of a three-dimensional finite element model that can simulate the forces applied while measuring the shear strength of the asphalt concrete pavement. A comparison between the model results and those obtained from available analytical models and field measurements proved the accuracy of the developed model.Key words: shear strength, in situ testing, finite element, asphalt, pavement, modelling.

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