7.3. Dynamic effects on building. 3.7.4. Noise. 3.7.5. Starting time requirements. 3.7.6. Life expectation. 3.7.7. Instructions. 4. Unusual verification tests. 4.1. General remarks. 4.2. Tests with non-axial load. 4.3. Buckling tests. 4.4. Tests with specification sets subjected to bending. 4.5. Fatigue performance of servo-controlled testing systems. 4.6. Constant load devices. 4.7. Constant load tests. 4.8. Tests with sudden variations of the specimen reaction. 4.9. Transition problems in block programming. 5. Comments. 5.1. General remarks. 5.2. Possible approaches to specification of performance. 5.3. Stiffness. 5.4. Effects on stress distribution in specimens. 5.5. Friction. 5.5.1. General remarks. 5.5.2. Effects of friction on gripping devices, etc. 5.5.3. Effects of friction in load measuring devices. 5.6. Accuracy. 5.7. Energy considerations. 6. Notation. 7. Index. 1. INTRODUCTION 1.1. Purpose

2021 ◽  
pp. 039139882199939
Author(s):  
Abdul Hadi Abdul Wahab ◽  
Nor Aqilah Mohamad Azmi ◽  
Mohammed Rafiq Abdul Kadir ◽  
Amir Putra Md Saad

Glenoid conformity is one of the important aspects that could contribute to implant stability. However, the optimal conformity is still being debated among the researchers. Therefore, this study aims to analyze the stress distribution of the implant and cement in three types of conformity (conform, non-conform, and hybrid) in three load conditions (central, anterior, and posterior). Glenoid implant and cement were reconstructed using Solidwork software and a 3D model of scapula bone was done using MIMICS software. Constant load, 750 N, was applied at the central, anterior, and posterior region of the glenoid implant which represents average load for daily living activities for elder people, including, walking with a stick and standing up from a chair. The results showed that, during center load, an implant with dual conformity (hybrid) showed the best (Max Stress—3.93 MPa) and well-distributed stress as compared to other conformity (Non-conform—7.21 MPa, Conform—9.38 MPa). While, during eccentric load (anterior and posterior), high stress was located at the anterior and posterior region with respect to the load applied. Cement stress for non-conform and hybrid implant recorded less than 5 MPa, which indicates it had a very low risk to have cement microcracks, whilst, conform implant was exposed to microcrack of the cement. In conclusion, hybrid conformity showed a promising result that could compromise between conform and non-conform implant. However, further enhancement is required for hybrid implants when dealing with eccentric load (anterior and posterior).


2015 ◽  
Vol 41 (3) ◽  
pp. 258-263 ◽  
Author(s):  
Angélica Castro Pimentel ◽  
Marcello Roberto Manzi ◽  
Cristiane Ibanhês Polo ◽  
Claudio Luiz Sendyk ◽  
Maria da Graça Naclério-Homem ◽  
...  

The aim of this study was to evaluate the stress distribution of different retention systems (screwed, cemented, and mixed) in 5-unit implant-supported fixed partial dentures through the photoelasticity method. Twenty standardized titanium suprastructures were manufactured, of which 5 were screw retained, 5 were cement retained, and 10 were mixed (with an alternating sequence of abutments), each supported by 5 external hexagon (4.0 mm × 11.5 mm) implants. A circular polariscope was used, and an axial compressive load of 100 N was applied on a universal testing machine. The results were photographed and qualitatively analyzed. We observed the formation of isochromatic fringes as a result of the stresses generated around the implant after installation of the different suprastructures and after the application of a compressive axial load of 100 N. We conclude that a lack of passive adaptation was observed in all suprastructures with the formation of low-magnitude stress in some implants. When cemented and mixed suprastructures were subjected to a compressive load, they displayed lower levels of stress distribution and lower intensity fringes compared to the screwed prosthesis.


2007 ◽  
Vol 30 (3) ◽  
pp. 479-486 ◽  
Author(s):  
K. Hill ◽  
S. C. Jenkins ◽  
D. L. Philippe ◽  
K. L. Shepherd ◽  
D. R. Hillman ◽  
...  

Author(s):  
Moncef Souissi

The capacity-to-torque ratio, Kt, has been used in the design of helical piles and anchors for over half a century. Numerous research efforts have been conducted to accurately predict this capaci-ty-to-torque ratio. However, almost of all these Kt factors are based on shaft geometry alone. The ca-pacity-to-torque ratio described herein was found to depend on the shaft diameter, shaft geometry, helix configuration, axial load direction, and installation torque. In this study, 799 full scale static load tests in compression and tension were conducted on helical piles of varying shaft diameters, shaft geometry, and helix configurations in different soil types (sand, clay, and weathered bedrock). The collected data were used to study the effect of these variables on the capacity-to-torque ratio and resulted in developing a more reliable capacity-to-torque ratio, Km, that considers the effect of the variables mentioned above. The study shows that the published Kt values in AC358 (ICC-ES Acceptance Criteria for Helical Piles Systems and Devices) underestimate the pile capacity at low torque and overestimate it at high torque. In addition, and based on probability analysis, the predicted capacity using the modified Km results in a higher degree of accuracy than the one based on the published Kt values in AC358.


2009 ◽  
pp. 416-416-19
Author(s):  
TD Lu ◽  
JA Fischer ◽  
VG Miller
Keyword(s):  

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. Lässing ◽  
R. Falz ◽  
C. Pökel ◽  
S. Fikenzer ◽  
U. Laufs ◽  
...  

AbstractWearing face masks reduce the maximum physical performance. Sports and occupational activities are often associated with submaximal constant intensities. This prospective crossover study examined the effects of medical face masks during constant-load exercise. Fourteen healthy men (age 25.7 ± 3.5 years; height 183.8 ± 8.4 cm; weight 83.6 ± 8.4 kg) performed a lactate minimum test and a body plethysmography with and without masks. They were randomly assigned to two constant load tests at maximal lactate steady state with and without masks. The cardiopulmonary and metabolic responses were monitored using impedance cardiography and ergo-spirometry. The airway resistance was two-fold higher with the surgical mask (SM) than without the mask (SM 0.58 ± 0.16 kPa l−1 vs. control [Co] 0.32 ± 0.08 kPa l−1; p < 0.01). The constant load tests with masks compared with those without masks resulted in a significantly different ventilation (77.1 ± 9.3 l min−1 vs. 82.4 ± 10.7 l min−1; p < 0.01), oxygen uptake (33.1 ± 5 ml min−1 kg−1 vs. 34.5 ± 6 ml min−1 kg−1; p = 0.04), and heart rate (160.1 ± 11.2 bpm vs. 154.5 ± 11.4 bpm; p < 0.01). The mean cardiac output tended to be higher with a mask (28.6 ± 3.9 l min−1 vs. 25.9 ± 4.0 l min−1; p = 0.06). Similar blood pressure (177.2 ± 17.6 mmHg vs. 172.3 ± 15.8 mmHg; p = 0.33), delta lactate (4.7 ± 1.5 mmol l−1 vs. 4.3 ± 1.5 mmol l−1; p = 0.15), and rating of perceived exertion (6.9 ± 1.1 vs. 6.6 ± 1.1; p = 0.16) were observed with and without masks. Surgical face masks increase airway resistance and heart rate during steady state exercise in healthy volunteers. The perceived exertion and endurance performance were unchanged. These results may improve the assessment of wearing face masks during work and physical training.


2016 ◽  
Vol 142 (5) ◽  
pp. 04016001 ◽  
Author(s):  
Hyeon-Jong Hwang ◽  
Tae-Sung Eom ◽  
Hong-Gun Park ◽  
Seung-Hwan Lee

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