Investigations Regarding Repeatability of Small Strokes of Electrically Activated SMA Wires

2020 ◽  
Author(s):  
Benedict Theren ◽  
Thomas Glaser ◽  
Antonia Weirich ◽  
Bernd Kuhlenkötter
Keyword(s):  
Shape Memory ◽  
Mechanical Load ◽  
Operational Reliability ◽  
The Other ◽  
Electrical Activation ◽  
Resistance Heating ◽  
Test Rig ◽  
Spring Force ◽  
The Wire ◽  
Small Stroke

Abstract This work makes a contribution regearding research of the generation of small strokes of electrically activated shape memory actuator wires. Binary Ni50Ti50 wires of 100 mm length and diameter of 0.3mm are investigated. Within the scope of this work, a test rig has been designed and built to carry out the performed experiments. One side of the wire was fixed while the other side worked against a spring. The spring force provided the resetting of the wire. The spring constant was chosen low to avoid a strong influence of the spring deflection on the force. The activation of the shape memory effect of the wires on this test rig was executed electrically by resistance heating and the adjustment of the mechanical load has been solved by pretensioning the spring. Four series of tests have been carried out to determine the feasibility and operational reliability of small stroke ranges. The focus here is on whether such strokes can be generated at all by means of electrical activation and on the other hand, how precisely these strokes can be achieved repeatably.

The Influence of Initial Commutator Surface Roughness on Wear of the Starter Motor Commutation System

2014 ◽  
Vol 966-967 ◽  
pp. 96-102
Author(s):  
Tanja Spremberg ◽  
Ingo Engler ◽  
Berend Denkena
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Mechanical Load ◽  
Life Time ◽  
The Other ◽  
Initial Surface ◽  
Test Rig ◽  
Starter Motor ◽  
Tribological System ◽  
Load Tests

One way to improve the run-in period of the commutation system of an electrical motor is the modification of the commutator ́s roughness. The reduction of the run-in period affects the wear during the motor life time. Therefore, within this paper the influence of the initial commutator roughness on the run-in period and the electromechanical wear is investigated. The research is done with a special starter components test rig. During the tests the wear is analyzed while the applied electromechanical and mechanical load is varied in order to enforce different wear behaviors. It is expected that with an optimal initial surface roughness the amount of wear is reduced until the steady state has been reached. However, the results revealed that there is no significant influence of the initial surface roughness on the examined electromechanical tribological system. It was found, that the mechanical wear of the commutator and the brushes is similar to the electromechanical wear during the run-in period. The run-in period of the mechanical load tests is shorter compared to the other experiments.

Modelling and Validation of a Rotary Motor Combining Shape Memory Wires and Overrunning Clutches

2014 ◽  
Author(s):  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Electrical Activation ◽  
Constant Force ◽  
Experimental Characterization ◽  
Low Friction ◽  
The Wire ◽  
Rotary Motor ◽  
Static Simulation

The paper presents the conceptual design, modeling and prototyping of a novel rotary motor based on shape memory alloy (SMA) wires. The basic architecture of the device capitalizes on a SMA wire wound around a low-friction cylindrical drum. The backup force to the SMA wire is provided by a beam spring which generates a nearly-constant force tangential to the drum. The electrical activation of the wire produces a contraction of the wire, hence a rotation of the drum fitted to the shaft through an overrunning clutch (free wheel). Thanks to the overrunning clutch, during the backup phase (recoiling of the wire), the drum rotates backward while the shaft does not move. Spurious backward movements of the shaft are contrasted by a second overrunning clutch linking the shaft to the frame. The paper presents a model for the quasi-static simulation of the motor and the experimental characterization of a prototype device featuring three active drums, a rotary sensor and an angular brake to apply the external load.

scholarly journals 28 SIMPLIFIED ACTIVATION METHOD TO IMPROVE THE IN VITRO DEVELOPMENT OF HANDMADE CLONED (HMC) PORCINE EMBRYOS

2009 ◽  
Vol 21 (1) ◽  
pp. 114
Author(s):  
Y. Du ◽  
Z. Yang ◽  
B. Lv ◽  
L. Lin ◽  
P. M. Kragh ◽  
...  
Keyword(s):  
Cell Number ◽  
Activation Method ◽  
The Other ◽  
Electrical Activation ◽  
In Vitro Development ◽  
Reconstructed Embryos ◽  
Fetal Fibroblasts ◽  
Group 2 ◽  
Vitro Development

Delayed activation is commonly used in pig somatic cell nuclear transfer (SCNT) where electrical activation is followed by chemical activation. However, chemical incubation of several hours (up to 4 or 6) is logistically not very convenient even though handmade cloning (HMC) could improve the overall efficiency of pig cloning (Du et al. 2007 Theriogenology 68, 1104–1110). It was reported that a brief exposure of cycloheximide (CX) before electrical activation could significantly increase developmental rate and total blastocyst cell number when simultaneous activation was performed in micromanipulator-based pig cloning (Naruse et al. 2007 Theriogenology 68, 709–716). The purpose of our present work is to investigate whether such activation method is also applicable for pig HMC. Data were analyzed by t-test using SPSS (11.0, SPSS Inc., Chicago, IL, USA). After 42 h in vitro maturation, cumulus cells were removed. In vitro-cultured porcine fetal fibroblasts were used as donor cells. Cytoplast-fibroblast pairing, electrical fusion and activation of fused cytoplast-fibroblast pairs were performed as described previously (Kragh et al. 2005 Theriogenology 64, 1536–1545; Du et al. 2005 Cloning Stem Cells 7, 199–205). Three groups were compared due to different activation protocol. In Group 1 (control), reconstructed embryos were cultured in porcine zygote medium 3 (PZM3) supplemented with 4 mg mL–1 BSA, 5 μg mL–1 cytochalasin B (CB), and 10 μg mL–1 CX for 4 h. In Group 2 (CX priming), fused pairs and the other halves of cytoplasts were incubated in HEPES-buffered TCM-199 medium supplemented with 10% calf serum, 10 μg mL–1 CX for 10 min just before the second fusion or electrical activation. In Group 3 (CB + CX priming), treatment similar to Group 2 was performed except that additional 5 μg mL–1 CB was added for the 10-min incubation. Reconstructed embryos were in vitro cultured in the well of the well (WOW) system for 6 days. Blastocyst rates and total cell numbers of Day 6 blastocysts were evaluated. As illustrated in Table 1, embryos pretreated with both CB and CX gave the best results, with better blastocyst formation (53.8 ± 4.8%; mean ± SEM) and higher cell number (77.2 ± 5.4) compared to the other 2 groups. Our data suggested that CX and CB priming could be used as a solution to the long chemical incubation in porcine SCNT by HMC, making the embryos more receptive to electrical activation. Table 1.In vitro development of HMC reconstructed embryos with different activation protocols

Experimental Investigation of High-Speed/High-Voltage SMA Actuation

2017 ◽  
Author(s):  
Paul Motzki ◽  
Tom Gorges ◽  
Thomas Würtz ◽  
Stefan Seelecke
Keyword(s):  
Shape Memory ◽  
High Voltage ◽  
Supply Voltage ◽  
High Energy ◽  
Wire Diameter ◽  
High Current ◽  
Sma Actuator ◽  
The Wire ◽  
Supply Voltages ◽  
A Current

The thermal shape memory effect describes the ability of a deformed material to return to its original shape when heated. This effect is found in shape memory alloys (SMAs) such as nickel-titanium (NiTi). SMA actuator wire is known for its high energy density and allows for the construction of compact systems. An additional advantage is the so-called “self-sensing” effect, which can be used for sensor tasks within an actuator-sensor-system. In most applications, a current is used to heat the SMA wires through joule heating. Usually a current between zero and four ampere is recommended by the SMA wire manufacturers depending on the wire diameter. Therefore, supply voltage is adjusted to the SMA wire’s electrical resistance to reach the recommended current. The focus of this work is to use supply voltages of magnitudes higher than the recommended supply voltages on SMA actuator wires. This actuation method has the advantage of being able to use industry standard voltage supplies for SMA actuators. Additionally, depending on the application, faster actuation and higher strokes can be achieved. The high voltage results in a high current in the SMA wire. To prevent the wire from being destroyed by the high current, short pulses in the micro- and millisecond range are used. As part of the presented work, a test setup has been constructed to examine the effects of the crucial parameters such as supply voltage amplitude, pulse duration, wire diameter and wire pre-tension. The monitored parameters in this setup are the wire displacement, wire current and force generated by the SMA wire. All sensors in this setup and their timing is validated through several experiments. Additionally, a highspeed optical camera system is used to record qualitative videos of the SMA wire’s behavior under there extreme conditions. This optical feedback is necessary to fully understand and interpret the measured force and displacement signals.

Improved Bond reliability through the use of Auxiliary Wires (Security Bumps and Stand-Off Stitch)

2010 ◽  
Vol 2010 (1) ◽  
pp. 000474-000478 ◽  
Author(s):  
David J Rasmussen ◽  
Rodney Thompson
Keyword(s):  
Circuit Design ◽  
Heat Affected Zone ◽  
High Reliability ◽  
Strength Properties ◽  
The Other ◽  
Wire Loop ◽  
The Wire ◽  
Die Bonding ◽  
Lower Loop ◽  
Major Impediment

Whether the need is due to poorly bondable materials, non-flat bonding surfaces, odd packaging situations, or just the need for high reliability; the integrity of a wire bond interconnect can usually be greatly improved through the proper use of Auxiliary Wires. Auxiliary Wires are defined as Security Wires, Security Bumps, or Stand-Off Stitch (aka Stitch on Bump). The old stand-by Security Wire has been an asset for several decades, however, this is being replaced by Security Bumps which require a smaller second bond termination area. Further, Stand-Off Stitch (SOS) has many more applications and also has many side benefits that could be incorporated into a circuit design for better wire strength properties, fewer interconnects (die to die bonding), and lower loops. Stand-Off Stitch bonding involves the placement of a ball bump at one end of the wire interconnect, then placing a wire with another ball at the other end of the interconnect and stitching off the wire on the previous placed ball bump. This results in a near homogeneous stitch bond interconnect to the bump with an inherent improvement in stitch bond pull strength. Another use for SOS is Reverse Bonding (Stitch bond on bump on die bond pad) often resulting in a lower loop profile than standard forward wire loop and the loop is stronger because the wire hasn't been work annealed above the ball (in the Heat Affected Zone). A major impediment to the implementation of SOS is the retraining of visual inspectors and the approval of quality departments.

Validation and optimization of a compact push-pull rubber actuator energized by an outer coil of shape memory wire

2020 ◽  
pp. 146442072097441
Author(s):  
Eugenio Dragoni ◽  
Giovanni Scirè Mammano
Keyword(s):  
Finite Element ◽  
Optimal Design ◽  
Shape Memory ◽  
Analytical Model ◽  
Axial Elongation ◽  
Present Concept ◽  
The Wire ◽  
High Level ◽  
Heating Up ◽  
Rubber Block

The authors have formerly published the analytical model and finite element validation of a push-pull actuator made by winding a thin shape memory wire on a solid rubber cylinder. The cylinder provides elastic backup for the wire upon cooling down and transforms its circumferential contraction into a magnified axial elongation upon heating up. Building on that study, this paper accomplishes three tasks: (1) build prototype actuators and perform simple tests to validate the theory; (2) develop simple procedures for the optimal design of the actuator starting from high-level engineering specifications; (3) envision how the present concept could be improved by replacing the rubber block with a compliant lattice-like or shell-like scaffold with designed properties to further enhance the axial stroke.

A novel “hitch-and-ride” deep biliary cannulation method during rendezvous endoscopic ultrasound-guided ERCP technique

Endoscopy ◽  
2017 ◽  
Vol 49 (10) ◽  
pp. 983-988 ◽  
Author(s):  
Yousuke Nakai ◽  
Hiroyuki Isayama ◽  
Saburo Matsubara ◽  
Hirofumi Kogure ◽  
Suguru Mizuno ◽  
...  
Keyword(s):  
Endoscopic Ultrasound ◽  
Event Rate ◽  
The Other ◽  
Adverse Event Rate ◽  
Technical Success ◽  
Ultrasound Guided ◽  
Endoscopic Retrograde ◽  
Biliary Cannulation ◽  
Technical Success Rate ◽  
The Wire

Abstract Background and study aim Endoscopic ultrasound-guided rendezvous (EUS-RV) is increasingly reported as a treatment option after failed endoscopic retrograde cholangiopancreatography. We developed a novel “hitch-and-ride” catheter for biliary cannulation to reduce the risk of guidewire loss during EUS-RV. Patients and methods We retrospectively evaluated safety and technical success of EUS-RV between June 2011 and May 2016. Biliary cannulation during EUS-RV using three methods – over-the-wire, along-the-wire, and hitch-and-ride – were compared. Results A total of 30 EUS-RVs were attempted and the technical success rate was 93.3 %, with two failures (one bile duct puncture and one guidewire insertion). After 28 cases of successful guidewire passage, cannulation was attempted by the over-the-wire (n = 13), along-the-wire (n = 4) or hitch-and-ride (n = 11) method. Only the hitch-and-ride method achieved biliary cannulation without guidewire loss or conversion to the other methods. Time to cannulation was shorter with the hitch-and-ride method (4 minutes) than with over-the-wire and along-the-wire methods (9 and 13 minutes, respectively). The adverse event rate of EUS-RV was 23.3 %. Conclusion A novel hitch-and-ride catheter was feasible for biliary cannulation after EUS-RV.

SHAPE MEMORY INVESTIGATION OF SMART CAMAR LOGO USING NITI ALLOY WIRE

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Muhammad Safwan Shuhaimi ◽  
Nubailah Abd. Hamid ◽  
Rosliza Razali ◽  
Muhammad Hussain Ismail
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Niti Alloy ◽  
Niti Shape Memory Alloy ◽  
Shape Effect ◽  
Niti Wire ◽  
The Wire ◽  
Reversible Phase

This project is investigates of NiTi shape memory alloy for simple smart application. The shape memory effect (SME) is attributed from the reversible phase transformation when subjected to stress and temperature. In this study, a small model of CAMAR logo was designed to mimic the shape memory effect. Three samples of wire were investigated; (i) Austenitic NiTi (ii) Martensitic NiTi and (iii) commercial plain carbon steel. The reversible austenite to martensite transformation of the NiTi wire was investigated by a differential scanning calorimetry (DSC) at temperatures ranging from -50 and 200oC. The wire was shaped into CAMAR logo using a mould and then heated at 500°C for 30 minutes in a high temperature furnace. To observe the shape effect recovery, the wire was straighten and reheated in warm water at different temperatures. Results showed that the austenitic wire exhibited complete shape memory recovery after heated at temperature approximately 35°C and  80°C. For the martensitic wire, complete recovery was only observed when the water temperature was ~ 80°C and no recovery was observed at ~30°C. This recovery effect was significantly influenced by the reversible phase transformation temperatures (PTTs) which attributed from the Austenite finish (Af) temperature.

Design Framework for Multi-Section Shape Memory Alloy Axial Actuators Considering Material and Geometric Uncertainties

2020 ◽  
Author(s):  
Weilin Guan ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Energy ◽  
High Energy Density ◽  
Design Framework ◽  
Efficient Design ◽  
Cross Sectional ◽  
Geometric Uncertainties ◽  
In Series ◽  
The Wire

Abstract Shape memory alloys are metallic materials with the capability of performing as high energy density actuators driven by temperature control. This paper presents a design framework for shape memory alloy (SMA) axial actuators composed of multiple wire sections connected in series. The various wire sections forming the actuators can have distinct cross-sectional areas and lengths, which can be modulated to adjust the overall thermomechanical response of the actuator. The design framework aims to find the optimal cross-sectional areas and lengths of the wire sections forming the axial actuator such that its displacement vs. temperature actuation path approximates a target path. Constraints on the length-to-diameter aspect ratio and stress of the wire sections are incorporated. A reduced-order numerical model for the multi-section SMA actuators that allows for efficient design evaluations is derived and implemented. An approach to incorporate uncertainty in the geometry and material parameters of the actuators within the design framework is implemented to allow for the determination of robust actuator designs. A representative application example of the design framework is provided illustrating the benefits of using multiple wire sections in axial actuators to modulate their overall response and approximate a target displacement vs. temperature actuation path.

Development of Anisotropy in Fibroblast Populated Collagen Gels

2002 ◽  
Author(s):  
Stavros Thomopoulos ◽  
Vedran Knezevic ◽  
Kevin D. Costa ◽  
Jeffrey W. Holmes
Keyword(s):  
Mechanical Properties ◽  
Soft Tissues ◽  
Mechanical Load ◽  
The Other ◽  
Collagen Structure ◽  
Collagen Gels ◽  
Specific Loading ◽  
Anisotropic Mechanical Properties ◽  
Muscle Loading ◽  
Heart Wall

The development of anisotropic mechanical properties is critical for the successful tissue engineering of many soft tissues. Load bearing tissues naturally develop varying degrees of anisotropy, presumably in response to their specific loading environment. For example, the heart wall develops a collagen structure that varies in a predictable manner through its depth [1]. Tendon, on the other hand, develops a matrix that does not vary much in orientation and is highly aligned in the direction of muscle loading [2]. These varied levels of anisotropy may be due to inherent differences between the cells in each tissue, to differences in the mechanical load and boundary conditions seen by the cells, or to a combination of these factors.

Sign in / Sign up

Export Citation Format

Share Document