scholarly journals Mechanics of Screw Joints Solved as Beams Placed in a Tangential Elastic Foundation

2021 ◽  
Vol 11 (12) ◽  
pp. 5616
Author(s):  
Karel Frydrýšek ◽  
Šárka Michenková ◽  
Leopold Pleva ◽  
Jan Koutecký ◽  
Jiří Fries ◽  
...  
Keyword(s):  
Biomechanical Model ◽  
Human Cadaver ◽  
Joint Models ◽  
Limit Values ◽  
Pull Out ◽  
Spruce Wood ◽  
Screw Joint ◽  
Non Linear ◽  
Deformation Force ◽  
Stress States

This article deals with a new original analytical solution of deformation, force and stress states in wood screw joints up to the limit values of pulling out/breaking the screw. The screws are under tension. The wood-to-screw interaction is effectively simplified by introducing several physical model variants using a tangential elastic non-linear foundation. The experimental verification of the proposed models using pull-out tests (i.e., pulling out screws from dry spruce wood in laboratory conditions) confirms the correctness of the proposed models of the elastic linear/non-linear foundation. The validity of the model is also analytically and experimentally verified in the biomechanical model of pulling out screws from the femur of a bovine/human cadaver, which confirms and expands the validity of newly designed screw joint models outside the timber structure area.

Influence of Temperature and Loading Rate on the Forming Limit Behaviour of Twin-Roll Cast, Rolled and Heat-Treated AZ31 as a Function of the Stress State

2016 ◽  
Vol 684 ◽  
pp. 67-73 ◽  
Author(s):  
Franz Berge ◽  
Thorsten Henseler ◽  
Christina Krbetschek ◽  
Madlen Ullmann ◽  
Rudolf Kawalla
Keyword(s):  
Stress State ◽  
Loading Rate ◽  
Sheet Thickness ◽  
Forming Limit ◽  
Limit Values ◽  
Loading Rates ◽  
Economic Production ◽  
Az31 Sheet ◽  
Limit Behaviour ◽  
Stress States

Magnesium and its alloys have high potential for lightweight applications in the automotive and aerospace industries. In order to design parts for new applications with optimized mechanical properties and higher, more economic production rates, the forming limit behaviour of thin sheets (t < 1.0 mm) has to be known for different temperatures and loading rates. In this study, forming limit curves of 0.8 mm thick AZ31 sheet were measured for deformation at 200 °C and 250 °C and at loading rates of 1 mm/s and 10 mm/s with the Nakajima test. The investigations showed that an increase in temperature from 200 °C to 250 °C tends toward higher forming limit values for all stress states. In contrast, an increase in the loading rate from 1 mm/s to 10 mm/s induces a reduction in formability. It can be seen that the temperature, loading rate, and stress state influence the force-distance curves, the distribution of the local major strains, and the sheet thickness reduction.

Bite performance surfaces of three ecologically divergent Iguanidae lizards: relationships with lower jaw bones

2019 ◽  
Vol 127 (4) ◽  
pp. 810-825
Author(s):  
Monique Nouailhetas Simon ◽  
Renata Brandt ◽  
Tiana Kohlsdorf ◽  
Stevan J Arnold
Keyword(s):  
Biomechanical Model ◽  
Disruptive Selection ◽  
Head Shape ◽  
Linear Combinations ◽  
Mechanical Advantage ◽  
Jaw Bones ◽  
Correlational Selection ◽  
Lower Jaw ◽  
Linear Selection ◽  
Non Linear

Abstract Traits that interact to perform an ecologically relevant function are expected to be under multivariate non-linear selection. Using the lower jaw morphology as a biomechanical model, we test the hypothesis that lower jaw bones of lizards are subjected to stabilizing and correlational selection, associated with mechanical advantage and maximum bite force. We used three closely related tropidurine species that differ in size, head shape and microhabitat: Eurolophosaurus nanuzae, Tropidurus hispidus and Tropidurus semitaeniatus. We predicted a common pattern of correlational selection on bones that are part of in-levers or part of the out-lever of the lower jaw. The predicted pattern was found in E. nanuzae and T. hispidus, but this could not be shown to be statistically significant. For T. semitaeniatus, we found significant disruptive selection on a contrast involving the surangular, and also significant directional selection on linear combinations of traits in all species. The results indicate that the non-linear selection on lower jaw bones does not reflect an optimum to enhance mechanical advantage in all species. Divergent functional demands and specific ecological contexts of species seem relevant in shaping patterns of selection on morphology.

Comparison of the Pull-Out Forces of Bioabsorbable Polylactide/Glycolide Screws (Biosorb and Lactosorb) and Tacks: A Study on the Stability of Fixation in Human Cadaver Parietal Bones

2002 ◽  
Vol 13 (4) ◽  
pp. 538-543 ◽  
Author(s):  
Johanna Tiainen ◽  
Sanna Leinonen ◽  
Jouko Ilomäki ◽  
Esa Suokas ◽  
Pertti Törmälä ◽  
...  
Keyword(s):  
Human Cadaver ◽  
Pull Out ◽  
The Stability ◽  
Parietal Bones

scholarly journals H ∞ Synthesis Method for Control of Non-linear Flexible Joint Models

2014 ◽  
Vol 47 (3) ◽  
pp. 8372-8377
Author(s):  
Patrik Axelsson ◽  
Goele Pipeleers ◽  
Anders Helmersson ◽  
Mikael Norrlöf
Keyword(s):  
Synthesis Method ◽  
Joint Models ◽  
Flexible Joint ◽  
Non Linear

Development of a shape memory alloy multiple-point injector for chemotherapy

2005 ◽  
Vol 219 (3) ◽  
pp. 213-217 ◽  
Author(s):  
W Xu ◽  
T G Frank ◽  
A Cuschieri
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Direct Injection ◽  
Element Model ◽  
Multiple Point ◽  
Linear Elastic ◽  
Outer Needle ◽  
Non Linear ◽  
Deformation Force ◽  
Medical Needle

A medical needle is described that allows injection to take place at multiple sites through a single stab wound. This is achieved by extruding multiple, thin, and curved internal needles from a larger, straight, outer needle. The development and finite element modelling of the shape memory alloy (SMA) inner needles is presented in this paper. A non-linear elastic element model was used in this process to allow for the non-linear properties of the alloy and the large deformations that occur. The model provided maximum strain values and penetration forces for the inner needles. The deformation force on the tip of the needle was measured against displacement to confirm the predicted penetration force. Applications for the device include the treatment of liver cancer by direct injection of alcohol into the tumours.

scholarly journals A New Pull-Out Technique for In-Place Estimation of Concrete Compressive Strength

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
F. Latte Bovio ◽  
G. Latte Bovio ◽  
A. Brencich ◽  
G. Cassini ◽  
D. Pera ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Stress State ◽  
Stress Distributions ◽  
Concrete Compressive Strength ◽  
Careful Choice ◽  
Pull Out ◽  
Compressive Stresses ◽  
New Type ◽  
Technical Details ◽  
Stress States

A new type of postinstalled wedge anchor (B15G) is presented. A refined geometry of the anchor bolt and a careful choice of all the technical details allow the insert to work also in tensile stress states and to avoid much of the practical uncertainties that affect the commonly used procedures. The calibration of the procedure has been performed on 3 classes of concrete and for 5 stress distributions (medium and low compression, vanishing stress states, inhomogeneous compressive stresses, and inhomogeneous tensile stresses). It has been found that the correlation curves, pull-out force versus compressive strength, are not linear and depend on the stress state; besides, the statistical scattering of the calibration tests never exceeds 7-8% of the average values.

scholarly journals A study to compare strengths of cadaveric tendon repairs with round-bodied and cutting needles

2021 ◽  
pp. 175319342110642
Author(s):  
Gino Vissers ◽  
Wan M. R. Rusli ◽  
Alexander Scarborough ◽  
Maxim D. Horwitz ◽  
Gordon J. McArthur ◽  
...  
Keyword(s):  
Failure Load ◽  
Flexor Tendon ◽  
Tendon Repair ◽  
Cadaver Study ◽  
Human Cadaver ◽  
Flexor Tendon Repair ◽  
Pull Out ◽  
Mode Of Failure ◽  
Traction Testing ◽  
Human Cadaver Study

This human cadaver study investigated whether flexor tendon repairs performed with round-bodied needles had a higher risk of pull-out compared with those performed with cutting needles. Forty human cadaver tendons were repaired (20 with each type of needle), subjected to tensile traction testing and evaluated by failure load and mode of failure. The average failure load was 50 N (SD 13 N) for tendons repaired with round-bodied needles, compared with 49 N (SD 16 N) for tendons repaired with cutting needles. Round-bodied needles resulted in more suture pull-out (18 out of 20 tendons) than cutting needles (6 out of 20 tendons). We found no differences in failure load, but significant differences in the mode of failure between round-bodied and cutting needles when used for cadaveric flexor tendon repair.

Non-linear explicit μFE models accurately predict axial pull-out force of cortical screws in human tibial cortical bone

2021 ◽  
pp. 105002
Author(s):  
Marzieh Ovesy ◽  
Juan Diego Silva-Henao ◽  
James W.A. Fletcher ◽  
Boyko Gueroguiev ◽  
Philippe K. Zysset ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Pull Out ◽  
Non Linear ◽  
Tibial Cortical Bone
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