Shape Memory Alloy Clip for Compression Colonic Anastomosis

2004 ◽  
Vol 127 (2) ◽  
pp. 351-354 ◽  
Author(s):  
Chengli Song ◽  
Tim Frank ◽  
Alfred Cuschieri
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Computer Aided Design ◽  
Colonic Anastomosis ◽  
Material Model ◽  
Colon Surgery ◽  
Thermomechanical Properties ◽  
Nonlinear Material ◽  
Element Analysis ◽  
And Performance

This study was setup to investigate the design and performance of a shape memory alloy clip for colonic anastomosis. The thermomechanical properties of the shape memory alloy material were studied and the data were used to derive a nonlinear material model. This enabled the development of computer computer aided design models and finite element analysis of the clip and tissue compression. The maximum strain of the anastomosis clip was within the recoverable range, and it exerted parallel compression of the colonic walls with a uniform pressure distribution. The design of the anastomosis clip was optimized for safe, simple, and effective use in colon surgery.

3D PRINTED HEXAPOD ROBOT ACTUATED BY SHAPE MEMORY ALLOY SPRINGS: DESIGN AND PERFORMANCE ANALYSIS

2021 ◽  
Author(s):  
Edilberto Alves de Abrantes Júnior ◽  
Augusto Figueiredo ◽  
Carlos Jose de Araujo ◽  
Raimundo Duarte
Keyword(s):  
Performance Analysis ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Hexapod Robot ◽  
3D Printed ◽  
And Performance

Structural fatigue and fracture of shape memory alloy actuators: Current status and perspectives

2021 ◽  
pp. 1045389X2110572
Author(s):  
Md Mehedi Hasan ◽  
Theocharis Baxevanis
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Current Status ◽  
Structural Fatigue ◽  
Sma Actuators ◽  
Empirical Relations ◽  
Fatigue And Fracture ◽  
And Performance ◽  
Commercial Applications ◽  
Crack Growth Rates

Shape Memory Alloy (SMA)-actuators are efficient, simple, and robust alternatives to conventional actuators when a small volume and/or large force and stroke are required. The analysis of their failure response is critical for their design in order to achieve optimum functionality and performance. Here, (i) the existing knowledge base on the fatigue and overload fracture response of SMAs under actuation loading is reviewed regarding the failure micromechanisms, empirical relations for actuation fatigue life prediction, experimental measurements of fracture toughness and fatigue crack growth rates, and numerical investigations of toughness properties and (ii) future developments required to expand the acquired knowledge, enhance the current understanding, and ultimately enable commercial applications of SMA-actuators are discussed.

scholarly journals Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Andrea D. Muschenborn ◽  
Keith Hearon ◽  
Brent L. Volk ◽  
Jordan W. Conway ◽  
Duncan J. Maitland
Keyword(s):  
Crosslink Density ◽  
Blood Clot ◽  
Shape Memory Polymer ◽  
Thermomechanical Properties ◽  
Recovery Stress ◽  
Element Analysis ◽  
Clot Removal ◽  
Acrylic Copolymers ◽  
Thrombectomy Device ◽  
And Performance

Purpose. To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods. Four thermoset acrylic copolymers containing benzyl methacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn∼512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole% BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

The Concept of Physical Metric in the Thermomechanical Modeling of Phase Transformations With Emphasis on Shape Memory Alloy Materials

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Vassilis P. Panoskaltsis ◽  
Lazaros C. Polymenakos ◽  
Dimitris Soldatos
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Phase Transformations ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Material Model ◽  
Internal Variable ◽  
Theoretical Interest ◽  
Numerical Examples ◽  
Thermomechanical Modeling

In this work we derive a new version of generalized plasticity, suitable to describe phase transformations. In particular, we present a general multi surface formulation of the theory which is capable of describing the multiple and interacting loading mechanisms, which occur during phase transformations. The formulation relies crucially on the consideration of the intrinsic material (“physical”) metric as a primary internal variable and does not invoke any decomposition of the kinematical quantities into elastic and inelastic (transformation induced) parts. The new theory, besides its theoretical interest, is also important for application purposes such as the description and the prediction of the response of shape memory alloy materials. This is shown in the simplest possible setting by the introduction of a material model. The ability of the model in simulating several patterns of the experimentally observed behavior of these materials such as the pseudoelastic phenomenon and the shape memory effect is assessed by representative numerical examples.

scholarly journals Tests on Pretrained Superelastic NiTi Shape Memory Alloy Rods: Towards Application in Self-Centering Link Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Xian Xu ◽  
Guangming Cheng ◽  
Junhua Zheng
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Strain Amplitude ◽  
Loading Rate ◽  
Mechanical Performance ◽  
Material Model ◽  
Niti Shape Memory Alloy ◽  
Test Results ◽  
Potential Applications ◽  
Strain Model

Austenitic shape memory alloy has potential applications in self-centering seismic resistant structural systems due to its superelastic response under cyclic tension. Raw austenitic SMA needs proper pretreatments and pretraining to gain a stable superelastic property. In this paper, tests are carried out to investigate the effects of pretraining, pretreatments, loading rate, and strain amplitude on the mechanical performance on austenitic SMA rods with a given size. The tested rods are to be used in a new concept self-centering steel link beam. Customized pretraining scheme and heat treatment are determined through the tests. The effects of loading rate and strain amplitude are investigated. A simplified stress-strain model for the SMA rods oriented to numerical simulations is obtained based on the test results. An example of using the simplified material model in numerical analysis of a self-centering steel link beam is conducted to validate the applicability of the model.

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