scholarly journals Discussion: “Two- and Three-Dimensional Cases of Stress Concentration, and Comparison With Fatigue Tests” (Peterson, R. E., and Wahl, A. M., 1936, ASME J. Appl. Mech., 3, pp. A15–A22)

1936 ◽  
Vol 3 (4) ◽  
pp. A146-A147
Author(s):  
Thomas J. Dolan
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Fatigue Tests

Improvement of performance of bolt-nut connections, Part I: Simulations

2014 ◽  
Vol 228 (17) ◽  
pp. 3069-3077 ◽  
Author(s):  
GH Majzoobi ◽  
M Agh-Mohammad Dabbagh ◽  
P Asgari ◽  
MK Pipelzadeh ◽  
SJ Hardy
Keyword(s):  
Numerical Simulation ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Numerical Simulations ◽  
Load Distribution ◽  
Inflection Point ◽  
Close Agreement ◽  
Three Dimensional ◽  
Fatigue Tests

The performance of bolt-nut connections can be improved by enhancing fatigue life of the connections. This can be accomplished by reducing the stress concentration in the threads of the connection. This investigation consists of two parts. In this part (part I), load distribution in threads of some ISO bolts is computed by three-dimensional numerical simulation and Stockley-proposed relations. The results show a close agreement between Stockley relations and the simulations for nearly all bolt sizes. The results indicate that stress concentration is nearly constant regardless of the bolt size. It is also found that the load percentage carried by the first thread varies from 35% for M6 and reaches to 58% for M20 and M30 ISO bolts. The results suggest that the rate of load distribution changes at a point of inflection, i.e. the rate after the inflection point diminishes as the bolt size decreases, whereas before this point, the trend of the rate is reversed. In part II (to be submitted separately), various techniques are employed for the reduction of stress concentration and enhancement of fatigue life of the connections. The techniques are evaluated by numerical simulations and fatigue tests.

Research of Fatigue Limit and Stress Concentration on Structural Steel with Double-Notches

2009 ◽  
Vol 419-420 ◽  
pp. 849-852
Author(s):  
Sheng Wu Wang ◽  
Shu Juan Sun ◽  
Ai Ling Wen ◽  
Wei Da Wang ◽  
Shinichi Nishida
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Fatigue Limit ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Notched Specimen ◽  
Blind Hole ◽  
Element Method

The fatigue limit of parts and components that have the multi-notches is important data for the design and manufacture of machinery and traffic equipment which are operated under the high speed or pressure. In this paper the rotating bending fatigue tests have been carried out to investigate the fatigue limit of specimen with double-notch that is constructed of step and blind hole, and analyzed the effect of stress concentrations at the double-notched bottoms on the fatigue limits, using three-dimensional elastic finite element method. Firstly, the fatigue tests of 8 group specimens have been performed for examining the of fatigue limits of the single-notched specimen and double-notched specimen, respectively. Additionally, the stress field interactions between two stress fields by the blind hole notch and step are discussed using three-dimensional elastic finite element method. The main results obtained in this study are as follows: The fatigue limit of the double-notched specimen are down comparison with the fatigue limit of the single-notched specimen; the fatigue limit of the double-notch specimen is insensitive to distance between the blind hole and step for the low carbon structure steel with better ductility; for the high-strength steel, superposition and intensification of the stress concentration by the blind hole and step mutually may be avoided so that their adverse effects on the fatigue strength may be become to minimize, as take appropriate distance between the blind hole and step. The results are significant for the design of engineering design of the multi-notched parts, and the study of fatigue strength.

Two- and Three-Dimensional Cases of Stress Concentration, and Comparison With Fatigue Tests

1936 ◽  
Vol 3 (1) ◽  
pp. A15-A22 ◽  
Author(s):  
R. E. Peterson ◽  
A. M. Wahl
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Practical Importance ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Carbon Steels ◽  
Dimensional Case ◽  
Strain Measurements

Abstract This paper reports the results of a study of some two- and three-dimensional cases of stress distribution with particular reference to shafts having fillets or transverse holes, these being of considerable practical importance. To determine the stress-concentration factor kt in such cases, strain measurements were made, using a specially developed extensometer with a gage length of 0.1 in. The results of these strain measurements indicate that for shaft fillets in bending (three-dimensional case) the stress-concentration factor kt is little different from the values obtained photoelastically on flat specimens having the same r/d ratio (a two-dimensional case). A comparison of these values of kt (both for shafts with fillets and with transverse holes), with data from fatigue tests, leads to the following observations: (1) In some cases fatigue results are quite close to theoretical stress-concentration values. (2) Fatigue results for alloy steels and quenched carbon steels are usually closer to theoretical values than are the corresponding fatigue results for carbon steels not quenched. (3) With decrease in size of specimen, the reduction in fatigue strength due to a fillet or hole becomes somewhat less; and for very small fillets or holes the reduction in fatigue strength is comparatively small. (4) Sensitivity factors determined for small specimens should not be applied to the design of machine parts regardless of size.

Studies in Three-Dimensional Photoelasticity: Stresses in Bent Circular Shafts With Transverse Holes—Correlation With Results From Fatigue and Strain Measurements

1944 ◽  
Vol 11 (1) ◽  
pp. A10-A16
Author(s):  
M. M. Frocht
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Pure Bending ◽  
Simple Method ◽  
Strain Measurements ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Considerable Work ◽  
Maximum Stresses

Abstract Bent circular shafts with holes in the plane of bending are of frequent occurrence in modern machines. They often form a part of the lubricating system as, for example, in the crankshafts of aircraft engines. Considerable work has been done to determine the maximum stresses and the factors of stress concentration in such shafts. The author presents a simple method of calculating such stresses for transverse holes in pure bending. Experimental photoelastic evidence that led to this method is given. A comparison of the stress-concentration factors obtained by it is made with the published results from fatigue tests and strain measurements from large steel shafts, which were performed a number of years ago at the Westinghouse Research Laboratories.

Stress analysis of some nut-bolt connections with modifications to the external shape of the nut

1987 ◽  
Vol 22 (4) ◽  
pp. 187-193 ◽  
Author(s):  
E A Patterson ◽  
B Kenny
Keyword(s):  
Shear Stress ◽  
Stress Concentration ◽  
Outer Surface ◽  
Maximum Stress ◽  
Maximum Shear Stress ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Steel Connections ◽  
Circumferential Groove ◽  
Stress Study

The effect on the stress levels in an axially loaded bolt has been investigated for the case where a nut which incorporated a circumferential groove in its outer surface was used. It was found from a three-dimensional photoelastic frozen stress study that the modified nut reduced the maximum stress in the bolt by 5 per cent. The addition of a bevel to the load bearing face of this nut further reduced the maximum stress to 74 per cent of its value in a standard connection. It has been established that these modifications reduce the maximum shear stress in the roots of the nut threads, and that the stress concentration associated with the groove was smaller than the maximum stress concentration in both the nut and bolt thread roots. The increase indicated by photoelastic analyses in the strength of the connection produced by these modifications, has also been substantiated by fatigue tests of steel connections, but these results are not reported in this paper.

Photoelastic Study and Fatigue Tests of a Contoured, Integrally Reinforced Branch Connection

1971 ◽  
Vol 93 (4) ◽  
pp. 1021-1029
Author(s):  
R. W. Schneider ◽  
W. M. Jackson ◽  
W. R. Nicolls
Keyword(s):  
Stress Concentration ◽  
Internal Pressure ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Bending Moment ◽  
Fatigue Tests ◽  
Extensive Study ◽  
Cylindrical Pressure Vessel ◽  
Concentration Factors ◽  
Stress Concentration Factors

The paper describes the results of an extensive study of a contoured, integrally reinforced branch connection in a cylindrical pressure vessel (or run pipe). Three epoxy models were tested by means of three-dimensional photoelasticity using the stress-freezing and slicing technique. Loads applied were internal pressure, a longitudinal moment on the branch, and a transverse bending moment on the branch; one model was required for each mode of loading. Stress distribution curves are given. In addition, thirteen geometrically similar steel headers were fatigue tested by longitudinal and transverse forces cyclically applied to the branch pipes. Tests were conducted over a range of nominal stress in the branch. Stress concentration factors or stress indices from the photoelastic tests for bending and stress intensification factors from the bending fatigue tests are compared. Stress concentration factors for internal pressure loading, as derived from the photoelastic tests, are presented. Since stress intensification factors are not used to describe fatigue behavior under pulsating pressure, a similar comparison is not possible. Owing to the amount of data accumulated, only the most pertinent are presented; in every instance this includes the area of maximum stress.

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