Nonlinear Effects on the Stresses and Deformations of Bolted Joints

1996 ◽  
Vol 118 (1) ◽  
pp. 54-58 ◽  
Author(s):  
T. F. Lehnhoff ◽  
W. E. Wistehuff
Keyword(s):  
External Load ◽  
Applied Load ◽  
Nonlinear Effects ◽  
Bolted Joints ◽  
Radial Position ◽  
Radial Location ◽  
Steel Members ◽  
Joint Separation ◽  
External Loads ◽  
Percent Decrease

Axisymmetric finite element modeling of bolted joints was performed to show the effects of the magnitude as well as the radial location of the externally applied load on the member separation radius and the stress on the surface between the two members. The separation radius was found to be nonlinearly related to changes in the magnitude as well as position of the external load. A 27-percent decrease for 24-mm bolts to 39-percent decrease for 8-mm bolts in the separation radius resulted with changes in the load magnitude. The external load varied from zero to the maximum that could be sustained before joint separation for steel members. The change in separation radius for the aluminum members, cast iron members, and a combination of the two materials was on the order of 2–10 percent. For the minimum and maximum external load, the separation radius decreased by 5 and 12 percent, respectively, with an increase in radial position of one to five bolt diameters for the 24-mm bolt models. Changes in the stress on the surface between the members also occurred with changes in magnitude as well as radial position of the external load. The stress was found to be higher near the bolt for larger external loads and also when the radial location of the external load was increased.

Nonlinear Effects on the Stiffness of Bolted Joints

1996 ◽  
Vol 118 (1) ◽  
pp. 48-53 ◽  
Author(s):  
T. F. Lehnhoff ◽  
W. E. Wistehuff
Keyword(s):  
Finite Element ◽  
Cast Iron ◽  
Finite Element Modeling ◽  
External Load ◽  
Nonlinear Effects ◽  
Bolted Joints ◽  
Radial Position ◽  
Bolted Joint ◽  
Element Modeling ◽  
Percent Decrease

Axisymmetric finite element modeling of bolted joints was performed to show the effects of the magnitude and position of the external load, member thickness, and member material on the bolt and member stiffnesses. The member stiffness of the bolted joint was found to decrease 10 to 42 percent for the 20-mm to 8-mm bolts, respectively, as the magnitude of the external load was increased. Member stiffness appears to be independent of the radial location of the external load and increases as the member thickness decreases. Member stiffness decreased by a factor of 2.5 to 3 with a change in the member material from steel to aluminum. The cast iron members had a decrease in member stiffness of a factor of 1.7 to 1.9. The aluminum over cast iron combination had a member stiffness between the aluminum and cast iron alone. Bolt stiffnesses varied by less than two percent for changes in the magnitude of the external load for all bolt sizes and member materials, except for the 8-mm bolt where stiffness increased by approximately 11 percent. Changes in radial position of the external load had no effect on the bolt stiffness. A 3 to 13-percent decrease in the bolt stiffness was found when changing from steel to aluminum members. A 2 to 3-percent bolt stiffness decrease resulted when the member material was changed from steel to cast iron and similarly from steel to the aluminum over cast iron combination

Effects of Bolt Threads on the Stiffness of Bolted Joints

2000 ◽  
Vol 123 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Terry F. Lehnhoff ◽  
Bradley A. Bunyard
Keyword(s):  
Finite Element Analysis ◽  
Cast Iron ◽  
External Load ◽  
Applied Load ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Joint Models ◽  
Element Analysis ◽  
Steel Members ◽  
Proof Strength

Axisymmetric finite element analysis (FEA) was performed on bolted joints to determine the effects of the threads on the bolt and member stiffnesses. For steel members, the member stiffness decreased 37.1, 37.7, 38.2, 41.0, and 49.4 percent for the 24, 20, 16, 12, and 8-mm-dia bolts, as the magnitude of the external load was increased. The external load was increased from zero to the value that caused the bolt force to equal its proof strength. The member stiffness for aluminum members decreased by 22.7 and 29.9 percent for the 24 and 20-mm bolts. The cast iron members had decreases of 26.9 and 32.3 percent for the 24 and 20-mm bolts. Likewise, the aluminum/cast iron members decreased in stiffness by 25.5 and 30.0 percent for the 24 and 20-mm bolts. The member stiffness with no external load applied decreased by approximately 65 percent when changing from steel to aluminum members, 53 percent from steel to cast iron, and 60 percent from steel to aluminum/cast iron. Bolt stiffness varied less than 1.4 percent over the total range of the externally applied load for each of the bolted joint models. The decrease in bolt stiffness for the 24 and 20-mm-dia bolts was approximately 4 percent when changing from steel to aluminum members, 7 percent when changing from steel to cast iron members, and 8 percent when changing from steel to aluminum/cast iron members. Comparison is made to research results which did not include the influence of the threads.

scholarly journals Associations between Well-Being State and Match External and Internal Load in Amateur Referees

2021 ◽  
Vol 18 (6) ◽  
pp. 3322
Author(s):  
Eñaut Ozaeta ◽  
Javier Yanci ◽  
Carlo Castagna ◽  
Estibaliz Romaratezabala ◽  
Daniel Castillo
Keyword(s):  
External Load ◽  
Contact Time ◽  
Well Being ◽  
Ground Contact ◽  
Internal Load ◽  
Match Play ◽  
Power Meter ◽  
Ground Contact Time ◽  
Training Impulse ◽  
External Loads

The main aim of this paper was to examine the association between prematch well-being status with match internal and external load in field (FR) and assistant (AR) soccer referees. Twenty-three FR and 46 AR participated in this study. The well-being state was assessed using the Hooper Scale and the match external and internal loads were monitored with Stryd Power Meter and heart monitors. While no significant differences were found in Hooper indices between match officials, FR registered higher external loads (p < 0.01; ES: 0.75 to 5.78), spent more time in zone 4 and zone 5, and recorded a greater training impulse (TRIMP) value (p < 0.01; ES: 1.35 to 1.62) than AR. Generally, no associations were found between the well-being variables and external loads for FR and AR. Additionally, no associations were found between the Hooper indices and internal loads for FR and AR. However, several relationships with different magnitudes were found between internal and external match loads, for FR, between power and speed with time spent in zone 2 (p < 0.05; r = −0.43), ground contact time with zone 2 and zone 3 (p < 0.05; r = 0.50 to 0.60) and power, speed, cadence and ground contact time correlated with time spent in zone 5 and TRIMP (p < 0.05 to 0.01; r = 0.42 to 0.64). Additionally, for AR, a relationship between speed and time in zone 1 was found (p < 0.05; r = −0.30; CL = 0.22). These results suggest that initial well-being state is not related to match officials’ performances during match play. In addition, the Stryd Power Meter can be a useful device to calculate the external load on soccer match officials.

scholarly journals Comparison between Continuous and Fractionated Game Format on Internal and External Load in Small-Sided Games in Soccer

2020 ◽  
Vol 17 (2) ◽  
pp. 405 ◽  
Author(s):  
Luís Branquinho ◽  
Ricardo Ferraz ◽  
Bruno Travassos ◽  
Mário C. Marques
Keyword(s):  
Confidence Intervals ◽  
External Load ◽  
Continuous Method ◽  
Soccer Players ◽  
Professional Soccer ◽  
Game Format ◽  
Physical Impact ◽  
Mean Differences ◽  
External Loads

This study aimed to identify the effects of continuous and fractionated game formats on internal and external load in small-sided games in soccer. Twenty male professional soccer players participated in the study performing the same exercise (5 vs. 5 players) continuously (1 × 24 min) and in a repeated/fractioned manner (2 × 12 min, 4 × 6 min, and 6 × 4 min). A comparison between playing conditions was assessed by means of standardized mean differences calculated with combined variance and respective confidence intervals of 90%. The limits for the statistics were 0.2, trivial; 0.6, small; 1.2, moderate; 2.0, large; and >2.0, very large. The results indicate that the use of the continuous method seems to present the tendency of less physical impact on the internal and external loads compared to the fractionated method. In addition, the higher number of exercise repetitions in the fractionated method was found to increase the external load compared to the continuous method. This study showed that application of small-sided games by the fractionated method tends to result in higher training loads.

Accurate Evaluation of Bolt and Clamped Members Stiffnesses Of Bolted Joints

2021 ◽  
Author(s):  
Rashique Iftekhar Rousseau ◽  
Abdel-Hakim Bouzid ◽  
Zijian Zhao
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Element Model ◽  
Fe Analysis ◽  
Bolted Joints ◽  
Analytical Models ◽  
Fe Modeling ◽  
Bolted Joint ◽  
A New Technique ◽  
External Loads

Abstract The axial stiffnesses of the bolt and clamped members of bolted joints are of great importance when considering their integrity and capacity to withstand external loads and resist relaxation due to creep. There are many techniques to calculate the stiffnesses of the joint elements using finite element (FE) modeling, but most of them are based on the displacement of nodes that are selected arbitrarily; therefore, leading to inaccurate values of joint stiffness. This work suggests a new method to estimate the stiffnesses of the bolt and clamped members using FE analysis and compares the results with the FE methods developed earlier and also with the existing analytical models. A new methodology including an axisymmetric finite element model of the bolted joint is proposed in which the bolts of different sizes ranging from M6 to M36 are considered for the analysis to generalize the proposed approach. The equivalent bolt length that includes the contribution of the thickness of the bolt head and the bolt nominal diameter to the bolt stiffness is carefully investigated. An equivalent bolt length that accounts for the flexibility of the bolt head is proposed in the calculation of the bolt stiffness and a new technique to accurately determine the stiffness of clamped members are detailed.

Analytical modeling of axial stiffness of tensile bolted joints under concentric external load

2019 ◽  
Vol 33 (11) ◽  
pp. 5285-5295 ◽  
Author(s):  
Peng He ◽  
Jiaxin Liu ◽  
Chengyuan Zhang ◽  
Zhansheng Liu
Keyword(s):  
External Load ◽  
Analytical Modeling ◽  
Bolted Joints ◽  
Axial Stiffness

Secondary Stresses in Airship Hull Structures

1927 ◽  
Vol 31 (204) ◽  
pp. 1073-1109
Author(s):  
J. F. Baker
Keyword(s):  
Cross Section ◽  
External Load ◽  
Structural Engineering ◽  
Secondary Stress ◽  
Rigorous Definition ◽  
The Cross ◽  
Definition Of ◽  
Redundant Structure ◽  
Ball Joints ◽  
External Loads

In no branch of structural engineering is there a rigorous definition of the term “secondary stress.”If the primary stresses in a structure are determined, that is, the stresses in the members due to an external load system, assuming that all the members are joined together by perfect pin- or ball-joints, then the secondary stresses are in general taken to be the additional stresses due to the rigidity of the actual joints used in practice.In such a highly redundant structure as an airship hull the labour involved, in determining even the primary stresses, precludes the use of the normal methods of stressing. It is usual to make use of generalised methods which give approximate results. These generalised methods imply that the external loads are applied to the structure in a certain distribution. Though this is rarely achieved, yet the results obtained are in most cases sufficiently accurate if suitable bracing is supplied to redistribute the external loads over the cross-section; the effect of the initial wrong distribution being then merely local.

An investigation into contact pressure distribution in bolted joints

2014 ◽  
Vol 228 (18) ◽  
pp. 3405-3418 ◽  
Author(s):  
JT Stephen ◽  
MB Marshall ◽  
R Lewis
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Applied Load ◽  
Plate Thickness ◽  
Operating Conditions ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Contact Pressure Distribution ◽  
Engineering Structures ◽  
Peak Value

Bolted joints are widely used in modern engineering structures and machine designs due to their low cost and reliability when correctly selected. Their integrity depends on quantitative representation of the contact pressure distribution at the interface during design. Because of the difficulty in reaching and assessing clamped interfaces with traditional experimental methods, presently bolted joint design and evaluation is based on theoretical analysis, with assumptions to quantify pressure distribution at the clamped interface, which may not represent their true operating conditions. The present work utilises a non-intrusive ultrasonic technique to investigate and quantify the pressure distribution in bolted joints. The effect of variation in plate thickness on the contact pressure distribution at bolted interfaces under varying axial loads is investigated. While it was observed that the contact pressure at the interface increases as the applied load increases, the distance from the edge of the bolt hole at which the distribution becomes stable is independent of the applied load on the bolted joint. However, the contact pressure distribution was observed to vary with the plate thickness. Although the variation in the peak value of the average contact pressure distribution in bolted joints does not depend on the plate thickness, the distance from the edge of bolt hole at which the value of the distribution becomes stable increases as the plate thickness is increased. It was also observed that the edge of the bolt head affected the position of the peak value of the contact pressure distribution at the interface, though its effect was dependent on plate thickness. Furthermore, a model based on a Weibull distribution has been proposed to fit the experimental data and a good correlation was observed.

External and internal Load and their Effects on Professional Volleyball Training

2020 ◽  
Vol 41 (07) ◽  
pp. 468-474
Author(s):  
Ricardo Franco Lima ◽  
Ana Silva ◽  
José Afonso ◽  
Henrique Castro ◽  
Filipe Manuel Clemente
Keyword(s):  
External Load ◽  
Inertial Measurement Unit ◽  
Perceived Exertion ◽  
Measurement Unit ◽  
Internal Load ◽  
Monitoring Process ◽  
Accurate Perception ◽  
Positive Correlations ◽  
The Impact ◽  
External Loads

AbstractThe purpose of this study was twofold: (i) characterize the external and internal training load of professional volleyball players with a focus on intra-week changes and (ii) test the relationships between internal and external load measures. Eight male professional players (age: 23.0±5.22 yo; body mass: 84.5 ± 7.58 kg; height: 193.0±9.71 cm; BMI: 22.0±0.02 kg/m2) were monitored daily over 15 weeks. The monitoring process included both internal (rate of perceived exertion [RPE] and session-RPE [s-RPE]) and external load variables, which were measured by an inertial measurement unit. Results revealed that, within-week variations revealed that RPE was significantly higher during MD-2 (d=0.59) and MD-3 (d=0.56) than MD-1. A significantly higher number of jumps was observed on MD-2 than MD-1 (d=0.69). Considering the relationships between internal and external load measures, small positive correlations were found between RPE and the number of jumps (r=0.17) and between s-RPE and the number of jumps (r=0.49). In conclusion, a tapering strategy was observed on the day before a match, as internal and external loads decreased. Both internal and external load measures are necessary to provide an accurate perception of the impact of training stimuli on players.

A Quasi-Static Model for Planar Compliant Parallel Mechanisms

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
Cyril Quennouelle ◽  
Clément Gosselin
Keyword(s):  
Parallel Mechanism ◽  
Applied Load ◽  
Jacobian Matrix ◽  
Static Model ◽  
Parallel Mechanisms ◽  
Compliance Matrix ◽  
End Effector ◽  
Kinematic Constraints ◽  
Compliant Parallel Mechanism ◽  
External Loads

In this paper, the mobility, the kinematic constraints, the pose of the end-effector, and the static constraints that lead to the kinematostatic model of a compliant parallel mechanism are introduced. A formulation is then provided for its instantaneous variation—the quasi-static model. This new model allows the calculation of the variation in the pose as a linear function of the motion of the actuators and the variation in the external loads through two new matrices: the compliant Jacobian matrix and the Cartesian compliance matrix that give a simple and meaningful formulation of the model of the mechanism. Finally, a simple application to a planar four-bar mechanism is presented to illustrate the use of this model and the new possibilities that it opens, notably the study of the kinematics for any range of applied load.

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