scholarly journals Problem of Pin Breakage in Equine Transfixation Pin Casting: Biomechanical Ex Vivo Testing of Four Different Pins

2019 ◽  
Vol 32 (03) ◽  
pp. 222-233
Author(s):  
Sara Keller ◽  
Sebastian Valet ◽  
Ann Martens ◽  
Bernhard Weisse ◽  
Anton Fürst ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Ex Vivo ◽  
Cyclic Fatigue ◽  
Fatigue Behaviour ◽  
Simplified Model ◽  
Testing Conditions ◽  
Metacarpal Bones ◽  
Ex Vivo Testing ◽  
Cycles To Failure ◽  
Steinmann Pin

Objective The aim of this study was to evaluate cyclic fatigue behaviour of a new pin with a thread run-out design in comparison with three other types of pins commonly used for equine transfixation pin casting. Materials and Methods Twenty-four pairs of equine cadaveric third metacarpal bones (MC3) equipped with one transfixation pin placed horizontally in the distal metaphysis were tested using a simplified model, mimicking the biomechanical situation of equine transfixation pin casting. A 6.3/8.0-mm Imex Duraface pin with thread run-out design (ITROP) was compared with a 6.1-mm smooth Steinmann pin (SSP), a Securos 6.2-mm, positive-profile pin (SPPP) and an Imex 6.3-mm, positive-profile pin (IPPP) under cyclic loading until failure in axial compression of MC3. Results All pins broke at clinically relevant load levels and cycle numbers. The SSP endured significantly (p = 0.0025) more cycles before failure (mean: 48685) than the ITROP (mean 25889). No significant differences in cycles to failure were observed comparing the SPPP versus ITROP, and the IPPP versus ITROP, respectively. Clinical Significance A thread run-out design does not necessarily lead to higher resistance against pin breakage under cyclic loading conditions. The SSP was most resistant against cyclic failure in these testing conditions, even though it was associated with more lateromedial displacement and cortical wear-out. This could outweigh reported disadvantages of the SSP such as reduced resistance to axial extraction and pin loosening.

The Effect of Reducing the Bone to Cast Distance in an Equine Transfixation Pin Cast: An Ex Vivo Biomechanical Study

2021 ◽  
Author(s):  
Caroline M. Bernath ◽  
Sebastian Valet ◽  
Fabrice Rossignol ◽  
Bernhard Weisse ◽  
Anton E. Fürst ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Ex Vivo ◽  
Biomechanical Study ◽  
Bone Surface ◽  
Outer Cortex ◽  
Test Set ◽  
Metacarpal Bones ◽  
Overall Stability ◽  
Set Up ◽  
Number Of Cycles

Abstract Objective The aim of this study was to evaluate the effect of reducing the bone to cast distance on the resistance of the pin to cyclic loading in equine transfixation pin casts. Study Design Eleven pairs of cadaveric equine third metacarpal bones were prepared and one 6.3/8.0 mm transfixation pin was placed in standard fashion 10 mm proximal to the distal physeal scar into each bone. One metacarpus of each pair was tested with a distance of 10 mm (10 mm group) and the contralateral metacarpus with a distance of 20 mm (20 mm group) between the outer cortex of the bone and the fixation of the pin. Eight pairs were tested using a simplified test set-up in which the pins were fastened at both ends to polyoxymethylene-copolymer sleeves. The pins of the remaining three pairs of bones were incorporated into a fibreglass cast. All specimens were tested under cyclic loading until failure of the pin in axial compression. Results All pins failed uni- or bilaterally at clinically relevant load levels. Pins of the 10 mm group endured significantly (p < 0.05) higher load levels and total number of cycles until failure compared with the pins of the 20 mm group. Conclusion The distance between the bone surface and the cast at the location of pin insertion has a significant effect on resistance of the pins to cyclic loading. Therefore, the amount of padding applied underneath an equine transfixation pin cast can have an influence on the overall stability and durability of the construct.

Behaviour of Stud Shear Connectors Subjected to Bi-Directional Cyclic Loading

2003 ◽  
Vol 6 (1) ◽  
pp. 65-75 ◽  
Author(s):  
R. Seracino ◽  
D. J. Oehlers ◽  
M. F. Yeo
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Cyclic Fatigue ◽  
Fatigue Behaviour ◽  
Shear Connectors ◽  
Rate Of Increase ◽  
Strength And Stiffness ◽  
Almost All ◽  
Existing Structure ◽  
Do So

Almost all stud shear connectors in composite steel-concrete bridge beams are subjected to bi-directional cyclic loading at some stage during the fatigue life of the structure. In the assessment of an existing structure, it is desirable to predict the extent of fatigue damage experienced by the stud shear connectors as accurately as possible as this component of the structure can not be visually inspected. However, very little research has been carried out to quantify the fatigue behaviour of stud shear connectors subjected to bi-directional cyclic loading. This paper presents a new push-pull specimen that was developed to provide a better understanding of the bidirectional cyclic fatigue behaviour of stud shear connectors. The tests confirmed that for a given range of load, the fatigue life of connectors subjected to bi-directional cyclic loading is longer than those subjected to unidirectional loads only, and that the strength and stiffness of the connectors reduce immediately upon cyclic loading and continues to do so throughout the fatigue life. It was also shown that the rate of increase in slip per cycle is constant over most of the fatigue life with a rapid increase near the end so that, if monitored, can be used to provide adequate warning of failure.

The Residual Stresses Generated by Deep Rolling and their Stability in Fatigue & Application to Deep-Rolled Crankshafts

2006 ◽  
Vol 524-525 ◽  
pp. 45-50 ◽  
Author(s):  
H. Michaud ◽  
Jean Michel Sprauel ◽  
F. Galzy
Keyword(s):  
Residual Stresses ◽  
Fatigue Resistance ◽  
Experimental Validation ◽  
Crack Arrest ◽  
Cyclic Fatigue ◽  
Rolling Process ◽  
Fatigue Behaviour ◽  
Deep Rolling ◽  
Bending Fatigue ◽  
Compressive Residual Stresses

In this work, the effect of steel grade on the fatigue resistance of deep-rolled crankshafts is analysed. In the first part of this paper, the mechanisms leading to the increase of the fatigue resistance brought by the deep rolling treatment, is presented. This reinforcement is mainly linked to crack arrest due both to a decrease of the in-depth stress concentration factor and to remaining compressive residual stresses induced by the deep rolling. In a second part, an analytical model of residual stresses generation by deep-rolling and fatigue is presented. In this model the low cyclic fatigue behaviour of the steel is taken into account, and the residual stress stability with bending fatigue cycling can be predicted. After a presentation of the experimental validation on two different microstructures (baintic and ferrito- perlitic), this model is used for analysing the main parameters of the deep-rolling process and fatigue resistance.

High cyclic fatigue behaviour of ultrafine grained Al 5083 alloy

2014 ◽  
Vol 30 (14) ◽  
pp. 1835-1842 ◽  
Author(s):  
D. Singh ◽  
P. Nageswara Rao ◽  
R. Jayaganthan
Keyword(s):  
Cyclic Fatigue ◽  
Fatigue Behaviour ◽  
Ultrafine Grained ◽  
Al 5083 Alloy

About Puncture Testing Applied for Mechanical Characterization of Fetal Membranes

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Wilfried Bürzle ◽  
Edoardo Mazza ◽  
John J. Moore
Keyword(s):  
Deformation Behavior ◽  
Mechanical Characterization ◽  
Ex Vivo ◽  
Fetal Membrane ◽  
Membrane Rupture ◽  
Resistance To Deformation ◽  
Ex Vivo Testing ◽  
Insight Into

Puncture testing has been applied in several studies for the mechanical characterization of human fetal membrane (FM) tissue, and significant knowledge has been gained from these investigations. When comparing results of mechanical testing (puncture, inflation, and uniaxial tension), we have observed discrepancies in the rupture sequence of FM tissue and significant differences in the deformation behavior. This study was undertaken to clarify these discrepancies. Puncture experiments on FM samples were performed to reproduce previous findings, and numerical simulations were carried out to rationalize particular aspects of membrane failure. The results demonstrate that both rupture sequence and resistance to deformation depend on the samples' fixation. Soft fixation leads to slippage in the clamping, which reduces mechanical loading of the amnion layer and results in chorion rupturing first. Conversely, the stiffer, stronger, and less extensible amnion layer fails first if tight fixation is used. The results provide a novel insight into the interpretation of ex vivo testing as well as in vivo membrane rupture.

scholarly journals Surgical management of ectrodactyly in a dog

2016 ◽  
Vol 37 (2) ◽  
pp. 891
Author(s):  
Márcio Poletto Ferreira ◽  
Marcelo Meller Alievi ◽  
Isis Dos Santos Dal-Bó ◽  
Fernanda Silveira Nóbrega ◽  
Paula Cristina Sieczkowski Gonzalez ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Distal Region ◽  
Soft Tissue Reconstruction ◽  
Tissue Separation ◽  
Elbow Luxation ◽  
Metacarpal Bones ◽  
Intramedullary Canal ◽  
Mongrel Dog ◽  
Tissue Reconstruction ◽  
Steinmann Pin

Ectrodactyly is the term used to designate cases in which soft and bone tissue separation within the distal region of the thoracic limbs is present. It is observed in particular below the metacarpal bones and extending to the radius and ulna. In addition, it can often be associated with ipsilateral elbow luxation. We describe a case of ectrodactyly in a 3-month-old mongrel dog, where bone and soft tissue separation occurred between the third and fourth digits, extending proximally to the carpal region. We identified shortening of the ulna without elbow luxation. The dog was subjected to a surgical procedure comprising bone and soft tissue reconstruction and ulnar diaphyseal osteotomy, which was fixed using a Steinmann pin in the intramedullary canal, maintaining a distance of 1 cm between the two ulnar fragments. Two distal phalanges were removed because it was not possible to reposition them anatomically in the limb. The dog walked with mild lameness nine months after surgery.

A Proximally-Adjustable Variable Length Intramedullary Nail: Ex Vivo Quasi-Static and Cyclic Loading Evaluation

2017 ◽  
Vol 11 (4) ◽  
Author(s):  
Mark J. Hedgeland ◽  
Alexander Martin Clark ◽  
Mario J. Ciani ◽  
Arthur J. Michalek ◽  
Laurel Kuxhaus
Keyword(s):  
Cyclic Loading ◽  
Mechanical Performance ◽  
Ex Vivo ◽  
Healing Process ◽  
Axial Loading ◽  
Torsional Stiffness ◽  
Axial Stiffness ◽  
Four Point Bending ◽  
Point Bend ◽  
Static And Cyclic Loading

An adjustable-length intramedullary (IM) nail may reduce both complications secondary to fracture fixation and manufacturing costs. We hypothesized that our novel nail would have suitable mechanical performance. To test this hypothesis, we manufactured three prototypes and evaluated them in quasi-static axial compression and torsion and quasi-static four-point bending. Prototypes were dynamically evaluated in both cyclic axial loading and four-point bending and torsion-to-failure. The prototypes exceeded expectations; they were comparable in both quasi-static axial stiffness (1.41 ± 0.37 N/m in cervine tibiae and 2.30 ± 0.63 in cadaver tibiae) and torsional stiffness (1.05 ± 0.26 N·m/deg in cervine tibiae) to currently used nails. The quasi-static four-point bending stiffness was 80.11 ± 09.360, greater than reported for currently used nails. A length-variance analysis indicates that moderate changes in length do not unacceptably alter bone-implant axial stiffness. After 103,000 cycles of axial loading, the prototype failed at the locking screws, comparable to locking screw failures seen clinically. The prototypes survived 1,000,000 cycles of four-point bend cyclic loading, as indicated by a consistent phase angle throughout cyclic loading. The torsion-to-failure test suggests that the prototype has adequate resistance to applied torques that might occur during the healing process. Together, these results suggest that our novel IM nail performs sufficiently well to merit further development. If brought to market, this adjustable-length IM nail could reduce both patient complications and healthcare costs.

scholarly journals Lipofection of early passages of cell cultures derived from murine adenocarcinomas: In vitro and ex vivo testing of the thymidine kinase/ganciclovir system

2002 ◽  
Vol 9 (1) ◽  
pp. 96-99 ◽  
Author(s):  
Armando L Karara ◽  
Viviana F Bumaschny ◽  
Gabriel L Fiszman ◽  
Cecilia C Casais ◽  
Gerardo C Glikin ◽  
...  
Keyword(s):  
Thymidine Kinase ◽  
Cell Cultures ◽  
Ex Vivo ◽  
Ex Vivo Testing

Fatigue Behaviour of Triaxial Braided Composites under Tension-Tension and Compression-Compression Loading

2019 ◽  
Vol 809 ◽  
pp. 23-28
Author(s):  
Florian Herrla ◽  
Helmut Rapp
Keyword(s):  
Cyclic Loading ◽  
Kink Band ◽  
Fatigue Behaviour ◽  
Stiffness Degradation ◽  
Braided Composites ◽  
Material Degradation ◽  
Band Formation ◽  
Compression Loading ◽  
Tension And Compression ◽  
Tension Loading

The fatigue behaviour of [0°/±45°] triaxial braided composites is investigated. Tension-tension and compression-compression loading is chosen to study main damage mechanisms and their effect on the stiffness degradation. In both cyclic loading cases a high stiffness degradation can be observed shortly after the start of cyclic loading. Inter-fibre fractures in the braid yarns with subsequent delaminations are responsible for this behaviour during tension-tension loading. Compression-compression loading leads to kink band formation in the axial yarns favoured by yarn undulations. In consequence of the observed material degradation, S-N curves based on a defined level of stiffness degradation are proposed for fatigue dimensioning instead of load cycles to fracture.

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