Evaluation of a metal acrylic repair product as a clamp for an external fixator

2004 ◽  
Vol 17 (02) ◽  
pp. 97-103 ◽  
Author(s):  
N. R. Gibson ◽  
R. A. Read ◽  
R. Day ◽  
I. D. Robertson ◽  
K. L. Staudte
Keyword(s):  
Mechanical Testing ◽  
Significant Variation ◽  
Significant Loss ◽  
External Fixators ◽  
Frame Design ◽  
Pullout Tests ◽  
Cyclical Loading ◽  
Cantilever Bending ◽  
Equivalent Strength ◽  
Loss Of Strength

SummaryMechanical testing was performed to evaluate an acrylic steel repair paste when used in the construction of external fixators. Individual pin-bar-acrylic constructs were compared with those made from Kirschner-Ehmer (KE) clamps or polymethylmethacrylate. The constructs were subjected to cantilever bending forces, pin-pullout tests and cantilever bending after undergoing cyclical fatigue. Forty mm segments of acrylic were significantly stronger than medium ESF clamps. Twenty-five mm segments of acrylic were of equivalent strength to clamps. Ten mm segments failed under physiological loads expected from dogs greater than 20 kg and were less likely to provide adequate pin coverage to protect against pin pull-put. The placement of a wire loop to secure the pin-bar intersects made application of the acrylic easier but did not alter stiffness. There was not any significant variation between different operators in the strength of their constructs nor tolerance of their constructs to pin pullout. Cyclical loading forces were applied to acrylic-pinbar units without significant loss of strength, and acrylic and polymethylmethacrylate units did not show any difference in stiffness after being subjected to cyclical fatigue. The acrylic steel repair paste is a handkneadable, fast setting, inexpensive and readily available acrylic for use in the construction of external fixators. It allows more flexibility in frame design than a clamp and on the basis of mechanical testing offers a very stiff and secure substitute for KE clamps or polymethylmethacrylate.

scholarly journals Study of the Efficiency of Ultrasonic Turning of Heat-Resistant Alloys with Tools from Mineral Ceramics

2019 ◽  
Vol 297 ◽  
pp. 01011
Author(s):  
Nguyen Khanh Toan ◽  
Nikolay Mezin
Keyword(s):  
Nickel Alloys ◽  
High Speed ◽  
Metal Removal ◽  
Ultrasonic Field ◽  
Significant Loss ◽  
Field Energy ◽  
Thermal Processes ◽  
Heat Resistant ◽  
Defective Layer ◽  
Loss Of Strength

The results of the study of the effectiveness of high-speed ultrasonic turning of billets from heat-resistant nickel alloys without coolant are given. It was established that the introduction of ultrasonic field energy into the shaping zone reduces the contact temperature by 10–15% and the cutting force by 20–30%. However, this does not cause a decrease in metal removal performance due to a significant loss of strength and ease of cutting at temperatures above 800 C. As follows from the results, ultrasound helps to reduce the thickness of the defective layer, the formation of which is caused by thermal processes and phase transformations with the appearance of tensile residual stresses in the surface layer.

Geotechnical characteristics of large rapid rock slides

2010 ◽  
Vol 47 (1) ◽  
pp. 116-132 ◽  
Author(s):  
James Glastonbury ◽  
Robin Fell
Keyword(s):  
High Strength ◽  
Significant Loss ◽  
Slide Mass ◽  
Geotechnical Characteristics ◽  
Lateral Margins ◽  
Internal Deformation ◽  
Strength Rock ◽  
First Time ◽  
Loss Of Strength ◽  
Rock Slides

Based on the analysis of 51 case studies of large rapid rock slides, for a landslide to travel rapidly after failure there has to be a significant loss of strength on the basal surface of rupture, lateral margins, and (or) internally within the slide mass, or the factor of safety has to be maintained below 1.0 after failure by high groundwater pressures. Internally sheared compound slides and translational slides may all travel rapidly depending on their detailed geotechnical and geometric characteristics. The characteristics of these landslides that suggest an increased likelihood of rapid failure have been identified. All the rapid rock slides examined in this study involved relatively high-strength rock masses. Most cases were considered to be first-time landslides, largely involving brittleness on the basal rupture surface. However, there were some cases considered to be reactivated or active landslides on pre-sheared rupture surfaces. For this latter group, the loss of strength leading to rapid landsliding was associated with brittle internal deformation or lateral margins.

scholarly journals Acción externa acelerada de sulfatos y cloruros en el estudio de la corrosión del acero en tracción en el hormigón armado

2017 ◽  
Vol 67 (328) ◽  
pp. 141
Author(s):  
M. A. G. Silva ◽  
M. P. Cunha ◽  
A. Pinho-Ramos ◽  
B. Sena da Fonseca ◽  
F. F. S. Pinho
Keyword(s):  
Compressive Strength ◽  
Sodium Sulfate ◽  
Concrete Beams ◽  
Significant Loss ◽  
Lower Porosity ◽  
Compressive Strength Of Concrete ◽  
Flexural Tests ◽  
Different Diameters ◽  
Steel Rebars ◽  
Loss Of Strength

Corrosion of the reinforcing steel may cause significant loss of strength of reinforced concrete structures. The study focuses on accelerating such corrosion and examining the degradation of (i) the compressive strength of concrete due to sodium sulfate in a wet atmosphere; and (ii) the flexural strength by a solution of sodium sulfate and sodium chloride. Three types of concrete were used and different beam specimens were reinforced by steel rebars of different diameters (6, 8 and 10mm), part of the beams being pre-cracked. The concrete with least strength allowed higher sulfate penetration along the entire process and the compressive strength increased slightly, possibly due to lower porosity of concrete after contamination. The results of the flexural tests showed decrease of strength in all cases. Pre-cracked beams exhibited smaller influence of porosity of concrete. Beams with 6mm rebars showed the largest loss of strength due to the contamination and corrosion process

Fresh Tympanic Membrane Perforations Heal Without Significant Loss of Strength

2005 ◽  
Vol 26 (6) ◽  
pp. 1100-1106 ◽  
Author(s):  
Anisur Rahman ◽  
Malou Hultcrantz ◽  
Joris Dirckx ◽  
Gregory Margolin ◽  
Magnus von Unge
Keyword(s):  
Tympanic Membrane ◽  
Significant Loss ◽  
Tympanic Membrane Perforations ◽  
Loss Of Strength

Microdamage at the pin-bone interface of external skeletal fixation pins after short-term cyclical loading ex-vivo

2003 ◽  
Vol 16 (02) ◽  
pp. 88-92 ◽  
Author(s):  
K. Cohen ◽  
R.P. McCabe ◽  
V.L. Kalscheur ◽  
R. Vanderby ◽  
M.D. Markel ◽  
...  
Keyword(s):  
External Fixation ◽  
Surface Density ◽  
Ex Vivo ◽  
Cortical Region ◽  
Basic Fuchsin ◽  
Short Term ◽  
Bone Interface ◽  
Cyclical Loading ◽  
Cantilever Bending

SummaryThis study determined microdamage associated with external fixation pin insertion and short-term cyclical loading, using an ex vivo ovine tibial model. Orthofix tapered blunt-tipped 3.5/4.5 mm fixation pins and Apex® self-drilling self-tapping fixation pins, 4 mm in diameter, were used. After insertion, the constructs were either loaded in cantilever bending or not loaded. Constructs were then bulk-stained in basic fuchsin, and calcified sections were made. The sections were reviewed qualitatively and the microcrack surface density (Cr.S.Dn, μm/mm2) was quantified at the pin-bone interface. The pattern and quantity of microdamage induced was significantly influenced by fixation pin design and cortical region within the cisor transcortex, but not short-term cyclical loading. Overall, Cr.S.Dn was significantly increased with use of the Orthofix fixation pin (P < 0.01). Cr.S.Dn was also increased in the medial cis-cortex, compared with the lateral transcortex (P < 0.05). Diffuse damage within the medial cis-cortex was higher with the Orthofix pin. In contrast, the Howmedica Apex® fixation pin caused fracture of the periosteal region of the lateral transcortex, but relatively little microdamage within the medial cis-cortex. In this model as a consequence of pin insertion, fixation pin design had significant specific damage effects on both the medial cis-cortex and the lateral trans-cortex

Tolerance of Upper Extremity Pneumatic Tourniquets and their Effect on Grip Strength

2008 ◽  
Vol 33 (3) ◽  
pp. 266-271 ◽  
Author(s):  
G. PRODHOMME ◽  
D. MOURAUX ◽  
P. -M. DUGAILLY ◽  
C. CHANTELOT ◽  
C. FONTAINE ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Grip Strength ◽  
Upper Extremity ◽  
Well Being ◽  
Linear Increase ◽  
Significant Loss ◽  
Healthy People ◽  
Contralateral Hand ◽  
Loss Of Strength

This study was undertaken to evaluate tourniquet tolerance in healthy people. An arm tourniquet was inflated to 100 mmHg above systolic blood pressure for 21 minutes. We measured pain and grip strength before, during and at various times after deflation. We tested 40 subjects (20 women and 20 men) with an average age of 38 (range 22–58) years. Eight individuals did not tolerate the tourniquet for this length of time and the test was stopped. Visual analogical scale had a globally linear increase during tourniquet application. We noted a sensation of well-being just after deflation, quickly replaced by pain in the tested limb due to limb reperfusion. We also noted a significant loss of strength in the tested limb, which completely recovered by 48 hours. We also observed a significant loss of strength in the contralateral hand, which also recovered by 48 hours. The possible reasons for these temporary losses of strength in both the ipsilateral and contralateral limbs are discussed.

Postpeak residual capacity of nailed connections of a shear wall

Holzforschung ◽  
2014 ◽  
Vol 68 (8) ◽  
pp. 987-992 ◽  
Author(s):  
Arijit Sinha
Keyword(s):  
Load Transfer ◽  
Peak Load ◽  
Shear Wall ◽  
Significant Loss ◽  
Bottom Plate ◽  
Maximum Loss ◽  
Residual Capacity ◽  
Plate Connection ◽  
Almost All ◽  
Loss Of Strength

Abstract To quantify the postpeak residual capacity and to gain insights into the load transfer mechanism of a shear wall, nail connection tests were performed on salvaged connections after a monotonic shear wall test loaded up to peak load. Experimental results reveal that there is a loss of strength in most of the fasteners studied, indicating that almost all the fasteners contribute toward racking resistance of the wall. The maximum loss of strength was observed for the fastener in the uplift corner and for the fastener along the middle stud. Another area where fasteners exhibited a significant loss of strength was in plate connection located at the bottom plate. The performance of a shear wall can be enhanced by strengthening the two areas – uplift corner and bottom plate.

scholarly journals EXPERIMENTAL ASSESMENT OF THE STRENGTH OF COACHES STRUCTURES AFTER COLLISION REPAIR

2016 ◽  
Author(s):  
Enrique Alcalá ◽  
David Rincón Dávila ◽  
Arturo Furones Crespo ◽  
Angel Luis Martín López
Keyword(s):  
Safety Issue ◽  
Bending Moment ◽  
Road Transport ◽  
Deformation Energy ◽  
Significant Loss ◽  
Fem Model ◽  
Hollow Section ◽  
Vehicle Type ◽  
Structural Deformations ◽  
Loss Of Strength

Vehicles repair after an accident and the quality assurance of the repair is a major safety issue. If the vehicle type category is M3, collective road transport vehicles, there is an additional concern due to their high number of occupants, the responsibility of third parties transport and the severity of some type of collisions such as rollovers. Moreover it has to be considered that the high cost of these vehicles and the investment made on them by the transport companies makes it profitable to proceed to their repair after some accidents. In this work it is quantified the loss of energy absorption capabilities of the structural steel profiles of rectangular hollow section used in the construction of these vehicles. The deformation energy has been measured by means of bending tests and calculating the bending moment vs bending angle curve. The load has been applied to reach 10, 15 and 20 permanent bending angles, representing those rollover structural deformations found on coach collisions of different severities. All test specimens have been straightened and bended up to 20 degrees some in the same bending direction as initial bend test and some in the opposite direction. The results show a significant loss of strength of the profiles and the final influence on a repaired structure has been quantified modeling with a FEM model a standard Regulation ECE 66 of Geneva type approval test. It is then demonstrated how it should be defined requirements for repaired buses and coaches after their repair of structural damages in collisions.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4040

scholarly journals What does ‘toughness’ look like? An examination of the breakdown of young and mature leaves under cyclical loading

2021 ◽  
Vol 11 (5) ◽  
pp. 20200087 ◽  
Author(s):  
Jordan Traff ◽  
David J. Daegling
Keyword(s):  
Mechanical Testing ◽  
Axial Loading ◽  
Testing System ◽  
Displacement Control ◽  
Gradual Decline ◽  
Leaf Toughness ◽  
Mature Leaves ◽  
Young Leaves ◽  
Cyclical Loading ◽  
Repetitive Loading

The material property of leaf toughness is considered the crucial mechanical challenge facing folivorous primates. Mature leaves have higher recorded toughness values than young leaves on average, leading to many assumptions about the patterning of food breakdown that follow a tough/not-tough dichotomy. We tested three hypotheses about how leaves break down under repetitive loading cycles, predicting that mature leaves (i) experience more force during simulated occlusal loads, (ii) more effectively resist fragmentation into small pieces, and (iii) show a more gradual decline in resistance over consecutive cycles than young leaves. Under displacement control using a mechanical testing system, we subjected young and mature leaves to 20 cycles of axial loading using interlocking steel wedges, then collected and quantified the size of the leaf fragments. While we found that mature leaves experienced more overall force than young leaves ( p < 0.001), they also shattered into smaller pieces ( p = 0.004) and showed a steeper decline in their resistance to the cycles over the course of a test ( p < 0.01). These results suggest that putatively ‘tougher’ foods (i.e. mature versus young leaves) do not necessarily resist fragmentation as commonly assumed. The current tough/not-tough paradigm of primate foods may not accurately reflect how leaves break down during masticatory behaviour.

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