The Effect of Thread Dimensional Conformance on Vibration-Induced Loosening

1999 ◽  
Vol 121 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Yubo Dong ◽  
Daniel P. Hess
Keyword(s):  
Cantilever Beam ◽  
Confidence Limit ◽  
Time To Failure ◽  
Dynamic Tests ◽  
Dimensional Conformance ◽  
Percent Confidence Limit

This paper presents the results from dynamic tests that investigate the effect of thread dimensional conformance of fasteners on vibration-induced loosening. Test specimens include combinations of bolts and nuts within dimensional conformance as specified by ASME Standard B1. 1-1992, as well as bolts with undersized pitch and major diameters and nuts with oversized pitch and minor diameters. Tests were performed using an inertial loaded compound cantilever beam apparatus that subjects the test fasteners to a vibration environment. Data from the tests show a significantly degraded resistance to vibration for the fastener combinations with undersized pitch and major bolt diameters or oversized pitch and minor nut diameters, compared to fastener combinations within conformance. Specifically, the lower 90 percent confidence limit for the time to failure for conforming specimens was 782 seconds compared to 8 to 29 seconds for nonconforming specimens.

scholarly journals Effect of synchronous irrigation on cyclic fatigue of nickel-titanium instrument in the dynamic and static models

2021 ◽  
Vol 19 ◽  
pp. 228080002098740
Author(s):  
Haiyun Liu ◽  
Yanfeng Li ◽  
Guangquan Chai ◽  
Yuan Lv ◽  
Changjian Li ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Flow Rate ◽  
Dynamic Control ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Control Group ◽  
Time To Failure ◽  
Dynamic Tests ◽  
Significant Difference ◽  
Experimental Group

Objective: To evaluate the effect of synchronous water irrigation on the fatigue resistance of nickel-titanium instrument. Methods: A standardized cyclic fatigue test models were established, and five types of nickel-titanium instruments (PTU F1, WO, WOG, RE, and M3) were applied. Each instrument was randomly divided into two groups ( N = 12). There was synchronous water irrigation in the experimental group, and no water irrigation in the control group. Besides, ProTaper Universal F1 was randomly divided into 10 groups ( N = 20). In the static group, nickel-titanium instruments were divided into one control group (no irrigation, N = 20) and six experimental group (irrigation, N = 20) based on different flow rate, angle and position; while in the dynamic group, instruments were divided into one control group (no irrigation, N = 20) and two experimental group (irrigation, N = 20) based on different flow rate. The rotation time (Time to Failure, TtF) of instruments was recorded and analyzed. Results: According to the static experiments, the TtF of instruments in all experimental groups was significantly higher than that in the static control group. Besides, the dynamic tests of PTU F1 showed that the TtF in the experimental group was significantly higher than that in the dynamic control group. Compared with control group, the TtF in the experimental groups increased by at least about 30% and up to 160%. The static and dynamic tests of PTU F1 showed that the TtF of nickel-titanium instrument in all experimental groups was significantly higher than that in the control group. However, there was no significant difference between any two experimental groups. Conclusion: Regardless of dynamic or static model, TtF with irrigation was longer than that with non-irrigation, indicating that synchronous irrigation can increase the fatigue resistance of nickel-titanium instrument. However, different irrigation conditions may have the same effect on the fatigue resistance.

A STATISTICAL COMPARISON OF FIVE GEODETIC GRAVIMETERS

Geophysics ◽  
1962 ◽  
Vol 27 (6) ◽  
pp. 889-891 ◽  
Author(s):  
John C. Behrendt
Keyword(s):  
Standard Deviation ◽  
North American ◽  
Confidence Limit ◽  
Statistical Comparison ◽  
Standard Deviations ◽  
Percent Confidence Limit

A statistical comparison of five LaCoste and Romberg geodetic gravimeters over the 5,129‐mgal North American calibration range shows an estimated standard deviation of 0.17 mgal for the set with a 90‐percent confidence limit of 0.28 mgal. Values for each meter, means and estimated standard deviations are presented for each of the 24 stations included in the set.

The Invisible Evil Twin of an Adrenal Adenoma

2019 ◽  
Vol 4 (1) ◽  
pp. 58
Author(s):  
Aimi Fadilah Mohamad ◽  
Fatimah Zaherah Mohamed Shah ◽  
Nur Aisyah Zainordin ◽  
Ur 'Aini Eddy Warman ◽  
Nazimah Ab Mumin ◽  
...  
Keyword(s):  
Adrenal Glands ◽  
Adrenal Adenoma ◽  
Definitive Diagnosis ◽  
Dynamic Tests ◽  
Venous Sampling ◽  
Aldosterone Secretion ◽  
Aldosterone Level ◽  
Suppression Test ◽  
The Right ◽  
Secondary Causes

Primary aldosteronism (PA) causes a persistently elevated blood pressure (BP) due to excessive release of the hormone aldosterone from the adrenal glands. Classically, it is called Conn’s syndrome and is described as the triad of hypertension and hypokalemia with the presence of unilateral adrenal adenoma. It can be cured with surgical resection of the aldosterone-secreting adenoma leading to resolution of hypertension, hypokalemia and increased cardiovascular risk associated with hyperaldosteronism. We present a case of a man with previous ischemic heart disease (IHD) who presented with resistant hypertension. Investigations for secondary causes of hypertension revealed an elevated aldosterone level and saline suppression test confirmed the diagnosis of PA. Radiological examination revealed a left adrenal adenoma and a normal right adrenal gland. However, adrenal venous sampling showed lateralization of aldosterone secretion towards the right. He subsequently underwent a laparoscopic right adrenalectomy which improved his BP control promptly. This case highlights the importance of recognizing the need to investigate for secondary causes of hypertension. It also underscores the importance of dynamic tests, which may not be easily accessible to most clinicians but should pursue, to allow a definitive diagnosis and effective treatment.

UNCERTAINTY QUANTIFICATION ON THE ADHESIVE LAYER FOR PASSIVE SHUNT CONTROL: CANTILEVER BEAM

2019 ◽  
Author(s):  
Luiz Felipe Ribas Motta ◽  
Guilherme Silva Prado ◽  
Venicio Silva Araujo ◽  
Heinsten Frederich Leal dos Santos
Keyword(s):  
Uncertainty Quantification ◽  
Cantilever Beam ◽  
Adhesive Layer ◽  
Shunt Control

Mathematical Modelling of a Cantilever Beam Driven by two Unbalanced Eletric Motors

2019 ◽  
Author(s):  
Arthur Mereles ◽  
Marcus Varanis ◽  
Anderson Langone Silva ◽  
José Manoel Balthazar ◽  
Eduardo Márcio de Oliveira Lopes ◽  
...  
Keyword(s):  
Mathematical Modelling ◽  
Cantilever Beam

Dynamic Tests on a New Large Wooden Vaulted Roof in Seismic Area

2001 ◽  
Vol 85 (4) ◽  
pp. 18-23
Author(s):  
Antonio Migliacci ◽  
Paolo Panzeri ◽  
Paola Ronca
Keyword(s):  
Dynamic Tests ◽  
Seismic Area
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