scholarly journals Mechanical Fatigue of Bovine Cortical Bone Using Ground Reaction Force Waveforms in Running

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Lindsay L. Loundagin ◽  
Tannin A. Schmidt ◽  
W. Brent Edwards
Keyword(s):  
Cortical Bone ◽  
Stress Fracture ◽  
Ground Reaction Force ◽  
Fatigue Behavior ◽  
Reaction Force ◽  
High Impact ◽  
Loading Rates ◽  
Mechanical Fatigue ◽  
Number Of Cycles ◽  
Cycles To Failure

Stress fractures are a common overuse injury among runners associated with the mechanical fatigue of bone. Several in vivo biomechanical studies have investigated specific characteristics of the vertical ground reaction force (vGRF) in heel-toe running and have observed an association between increased loading rate during impact and individuals with a history of stress fracture. The purpose of this study was to examine the fatigue behavior of cortical bone using vGRF-like loading profiles, including those that had been decomposed into their respective impact and active phase components. Thirty-eight cylindrical cortical bone samples were extracted from bovine tibiae and femora. Hydrated samples were fatigue tested at room temperature in zero compression under load control using either a raw (n = 10), active (n = 10), low impact (n = 10), or high impact (n = 8) vGRF profile. The number of cycles to failure was quantified and the test was terminated if the sample survived 105 cycles. Fatigue life was significantly greater for both impact groups compared to the active (p < 0.001) and raw (p < 0.001) groups, with all low impact samples and 6 of 8 high impact samples surviving 105 cycles. The mean (± SD) number of cycles to failure for the active and raw groups was 12,133±11,704 and 16,552±29,612, respectively. The results suggest that loading rates associated with the impact phase of a typical vGRF in running have little influence on the mechanical fatigue behavior of bone relative to loading magnitude, warranting further investigation of the mechanism by which increased loading rates are associated with stress fracture.

Ground reaction force and hoof deceleration patterns on two different surfaces at the trot

2006 ◽  
Vol 3 (4) ◽  
pp. 209-216 ◽  
Author(s):  
Pia Gustås ◽  
Christopher Johnston ◽  
Stig Drevemo
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Ground Surface ◽  
Ground Reaction Forces ◽  
Triaxial Accelerometer ◽  
Loading Rates ◽  
Sand Surface ◽  
Reaction Forces ◽  
Force Data

AbstractThe objective of the present study was to compare the hoof deceleration and ground reaction forces following impact on two different surfaces. Seven unshod Standardbreds were trotted by hand at 3.0–5.7 m s− 1 over a force plate covered by either of the two surfaces, sandpaper or a 1 cm layer of sand. Impact deceleration data were recorded from one triaxial accelerometer mounted on the fore- and hind hooves, respectively. Ground reaction force data were obtained synchronously from a force plate, sampled at 4.8 kHz. The differences between the two surfaces were studied by analysing representative deceleration and force variables for individual horses. The maximum horizontal peak deceleration and the loading rates of the vertical and the horizontal forces were significantly higher on sandpaper compared with the sand surface (P < 0.001). In addition, the initial vertical deceleration was significantly higher on sandpaper in the forelimb (P < 0.001). In conclusion, it was shown that the different qualities of the ground surface result in differences in the hoof-braking pattern, which may be of great importance for the strength of the distal horse limb also at slow speeds.

Does Delivery Length Impact Measures of Whole-Body Biomechanical Load During Pace Bowling?

2020 ◽  
Vol 15 (10) ◽  
pp. 1485-1489
Author(s):  
Samuel J. Callaghan ◽  
Robert G. Lockie ◽  
Walter Yu ◽  
Warren A. Andrews ◽  
Robert F. Chipchase ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Repeated Measures ◽  
Reaction Force ◽  
Practical Importance ◽  
Whole Body ◽  
Loading Rates ◽  
Biomechanical Loading ◽  
Repeated Measures Analysis ◽  
Load Monitoring ◽  
Monitoring Practice

Purpose: To investigate whether changes in delivery length (ie, short, good, and full) lead to alterations in whole-body biomechanical loading as determined by ground reaction force during front-foot contact of the delivery stride for pace bowlers. Current load-monitoring practices of pace bowling in cricket assume equivocal biomechanical loading as only the total number of deliveries are monitored irrespective of delivery length. Methods: A total of 16 male pace bowlers completed a 2-over spell at maximum intensity while targeting different delivery lengths (short, 7–10 m; good, 4–7 m; and full, 0–4 m from the batter’s stumps). In-ground force plates were used to determine discrete (vertical and braking force, impulse, and loading rates) and continuous front-foot contact ground reaction force. Repeated-measures analysis of variance (P < .05), effects size, and statistical parametrical mapping were used to determine differences between delivery lengths. Results: There were no significant differences between short, good, and full delivery lengths for the discrete and continuous kinetic variables investigated (P = .19–1.00), with trivial to small effect sizes. Conclusion: There were minimal differences in front-foot contact biomechanics for deliveries of different lengths (ie, short, good, and full). These data reinforce current pace bowling load-monitoring practices (ie, counting the number of deliveries), as changes in delivery length do not affect the whole-body biomechanical loading experienced by pace bowlers. This is of practical importance as it retains simplicity in load-monitoring practice that is used widely across different competition levels and ages.

Mechanical Fatigue Limit for Rubber

1966 ◽  
Vol 39 (2) ◽  
pp. 348-364 ◽  
Author(s):  
G. J. Lake ◽  
P. B. Lindley
Keyword(s):  
Fatigue Limit ◽  
Growth Behavior ◽  
Energy Characteristics ◽  
Mechanical Fatigue ◽  
Tearing Energy ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Limiting Value ◽  
Mechanical Rupture

Abstract Investigations of the dynamic cut growth behavior of vulcanized rubbers indicate that there is a minimum tearing energy at which mechanical rupture of chains occurs. The limiting value is characteristic of each vulcanizate, but is in the region of 0.05 kg/cm. The mechanical fatigue limit, below which the number of cycles to failure increases rapidly, is accurately predicted from this critical tearing energy. Characteristics of cut growth at low tearing energies, and effects of polymer, vulcanizing system, oxygen, and fillers on the critical tearing energy and fatigue limit are discussed.

Analysis of Mechanical Fatigue Behavior for MEMS Structures

2014 ◽  
Vol 511-512 ◽  
pp. 565-568
Author(s):  
Qin Wen Huang ◽  
Xiang Guang Li ◽  
Yun Hui Wang
Keyword(s):  
Rf Mems ◽  
Fatigue Testing ◽  
Electrostatic Force ◽  
Fatigue Behavior ◽  
Excitation Frequency ◽  
Material Degradation ◽  
Mems Switch ◽  
Mechanical Fatigue ◽  
Number Of Cycles ◽  
Alternating Voltage

Fatigue of MEMS structures may occur after cyclic vibration loading, which can lead to the material degradation. A test bench was built for mechanical fatigue testing, especially for the structures that actuated by electrostatic force. A RF MEMS switch which was made of gold was tested; the material mechanical characteristic was monitored during the tests by means of the value of pull-in voltage, which is related to the change of the Youngs modulus. The fatigue stress was produced by an alternating voltage, and the amplitude of which is from 15V to 65V. The excitation frequency and the actuation time were used as a counter for the number of cycles. The results show that there is no detectable mechanical fatigue after actuation up to one billion cycles.

SnAgCu Micro-Ball Grid Array (BGA) Solder Joint Evaluation Using a Torsion Mechanical Fatigue Test Method

2005 ◽  
Author(s):  
Claire Ryan ◽  
Bryan A. Rodgers ◽  
Jeff M. Punch
Keyword(s):  
Fatigue Test ◽  
Solder Joints ◽  
Fatigue Testing ◽  
Ball Grid Array ◽  
Test Method ◽  
Superior Performance ◽  
Cycle Number ◽  
Mechanical Fatigue ◽  
Number Of Cycles ◽  
Cycles To Failure

Due to the hazard which lead poses to health and the environment the EU is banning its use in electrical and electronic equipment from July 2006. This ban along with the market drive to more environmentally friendly products means that tin-lead solders must be replaced with lead-free alternatives. This paper presents the results of an experimental investigation of the mechanical fatigue properties of tin-silver-copper (SnAgCu) solder joints with a baseline of tin-lead (SnPb). The test vehicle comprised of an 8-layer FR4 printed circuit board (PCB) mounted with four micro-ball grid array (BGA) components — each with a total of 100 solder balls in a 10×10 array. The solder joints were formed using surface mount reflow processes optimised for both solder types. A torsion mechanical fatigue test was employed to evaluate the solder joints — the principle of which was to stress the solder joints repetitively in order to determine the number of cycles to failure. The BGA components were daisy-chained — the resistance across each daisy-chain was monitored continuously during the cyclic defection of the test board. A profile of the increase in resistance with cycle number was established and the number of cycles to failure determined. The failure mechanism induced by the cycling was examined using cross-section and scanning electron microscopy (SEM) techniques. The results for SnAgCu joints show a superior performance during torsion mechanical fatigue testing than SnPb joints; giving a greater number of cycles to failure. The results from the tests presented in this paper show that the torsion test method provides a viable alternative to ATC as a qualification method for solder joints, while also providing substantial time savings — taking weeks rather than months to complete.

scholarly journals An Updated Review of the Fatigue Behavior of Components Coated with Thin Hard Corrosion-Resistant Coatings

2014 ◽  
Vol 8 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Sergio Baragetti ◽  
Francesco Villa
Keyword(s):  
Numerical Models ◽  
Fatigue Behavior ◽  
Hard Coatings ◽  
Current Application ◽  
Current State ◽  
Numerical Characterization ◽  
Number Of Cycles ◽  
Corrosion Resistant Coatings ◽  
Cycles To Failure

In the present manuscript, an extended review on the state of the art on the experimental and numerical characterization of the fatigue behavior of Physically Vapor Deposited (PVD) and Chemically Vapor Deposited (CVD) thin hard coatings is presented. The current application and development fields of PVD and CVD treatments are analysed, focusing on the advantages granted by the adoption of these coatings for corrosion protection on various materials and components. The most recent experimental research results related to the fatigue behavior of PVD and CVD coated specimens are reported. Fatigue strength values are presented for various coating processes on different substrates, including hard steel as well as aluminium and titanium light alloys. Corrosion fatigue effects on coated specimens are presented where available, in order to evaluate the coating effectiveness in aggressive environments. An overview on the current state of development of theoretical and numerical models for the characterization of coated components and for the maximum number of cycles to failure is proposed to the reader.

The mechanical behavior of poly(lactic acid) unreinforced and nanocomposite films subjected to monotonic and fatigue loading conditions

2011 ◽  
Vol 45 (26) ◽  
pp. 2717-2726 ◽  
Author(s):  
Rodney D. Averett ◽  
Mary L. Realff ◽  
Karl Jacob ◽  
Mukerrem Cakmak ◽  
Baris Yalcin
Keyword(s):  
Lactic Acid ◽  
Fatigue Resistance ◽  
Failure Time ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Nanocomposite Films ◽  
Poly Lactic Acid ◽  
Loading Conditions ◽  
Number Of Cycles ◽  
Cycles To Failure

The mechanical and fatigue behavior of neat poly(lactic acid) (PLA) films and PLA films reinforced with 5 wt% nanoclay particles has been examined using various analytical procedures. The results showed that for the films tested in this study, PLA-5 wt% samples were more susceptible to crazing at the same maximum fatigue stress as the neat PLA samples, as evidenced by results from light transmission experiments. Optical microscopy results confirmed this observation. In addition, under fatigue loading conditions, the neat PLA samples displayed almost the same fatigue resistance (number of cycles to failure) at 3 and 30 Hz, while the PLA-5 wt% samples showed a shift in the number of cycles to failure to higher values at a frequency of 30 Hz. Using the linear regression curves from the S– N data (stress vs. number of cycles to failure), time-to-failure curves were generated to show the difference between the neat PLA and PLA-5 wt% samples when tested at frequencies of 3 and 30 Hz. Based on these results, it is known that the nanoclay particles served to increase the fatigue resistance at the higher frequency of 30 Hz, when compared to the neat PLA sample.

Estimation of the Fatigue Curve of a Wire Rope at Different Scales

2019 ◽  
Vol 820 ◽  
pp. 85-96 ◽  
Author(s):  
Achraf Wahid ◽  
Nadia Mouhib ◽  
Abdelkarim Kartouni ◽  
Hamid Chakir ◽  
Mohamed El Ghorba
Keyword(s):  
Crack Initiation ◽  
Fatigue Behavior ◽  
Fatigue Curve ◽  
Wire Rope ◽  
Unified Theory ◽  
Simplified Approach ◽  
Initiation Phase ◽  
Number Of Cycles ◽  
Wire Strand ◽  
Cycles To Failure

The wire rope 19 × 7 is a complex component, it consists of 18 strands in helical from around a central core strand, each strand consist of a 7 wires laid in helical. The friction in wire rope between wire and wire decrease its lifetime. For that, this study is an attempt to present a simplified approach to predict the lifetime of cable in three scale (wire, strand, cable) using unified theory and the Basquin's law, at the level of the strand scale we have estimated its fatigue behavior in the initiation phase and also within the number of the cycle to failure as well as the ratio of the number of cycles to crack initiation Ni to the number of cycles to failure, we based on the tensile test.

Sign in / Sign up

Export Citation Format

Share Document