Analysis of Cylindrical SMA Fan Clutch

2010 ◽  
Vol 148-149 ◽  
pp. 1643-1647
Author(s):  
Jian Min He ◽  
Jin Huang ◽  
Yu Xi Liu
Keyword(s):  
Shape Memory Alloy ◽  
Cooling System ◽  
Design Method ◽  
Cylindrical Shape ◽  
Helical Spring ◽  
Alloy Wire ◽  
Heating And Cooling ◽  
Sma Spring ◽  
Sma Helical Spring ◽  
The Relationship

This paper presents a cylindrical Shape memory alloy (SMA) fan clutch for automobile cooling system application. The resilience of pre-strain 2% SMA alloy wire is analyzed in the processes of heating and cooling. The Design method of SMA helical spring is described. The expression of transmission torque provided by SMA spring is established. The relationship between transmission torque and temperature is analyzed in detail. The results indicate that the transmission torque increases gradually with the increasing of airflow temperature and decreases with the decreasing of airflow temperature, respectively. The cylindrical SMA fan clutch has the property that its transmission torque changes rapidly according to the temperature of airflow from radiator.

A novel model-based approach for resistance estimation using rise time and sensorless position control of sub-millimetre shape memory alloy helical spring actuator

2017 ◽  
Vol 29 (6) ◽  
pp. 1050-1064 ◽  
Author(s):  
M Sreekanth ◽  
Abraham T Mathew ◽  
R Vijayakumar
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Rise Time ◽  
Position Control ◽  
Sensorless Control ◽  
Open Loop ◽  
Current Drive ◽  
Constant Current ◽  
Helical Spring ◽  
Heating And Cooling

Shape memory alloy shows considerable strain during heating and cooling. This effect is due to its phase transformation with temperature. Due to this property, shape memory alloys can be deployed for physical actuation in place of conventional actuators in bio-medical and bio-mimicking robots. Sub-millimetre diameter shape memory alloy wires wound as helical springs are also used for this purpose. Due to their small size, it is difficult to use sensors for temperature or displacement measurements of shape memory alloy springs. This article attempts to demonstrate that the rise time of the current through a sub-millimetre diameter shape memory alloy helical spring is directly proportional to its displacement. To characterize the rise time–displacement hysteresis, a constant current drive with overcurrent protection is developed. The data generated are utilized to implement an open-loop sensorless control. A method to estimate the resistance from the rise time is proposed with which the temperature of the shape memory alloy during actuation can be obtained. The design avoids using an analogue-to-digital converter for the direct measurement of voltage and current for measuring the resistance variation in the shape memory alloy under actuation. This helps in the development of a new sensorless control using only the digital Input/Output pins of a microcontroller/microprocessor.

scholarly journals Behaviour of NiTi SMA Helical Springs under Different Temperatures and Deflections

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
R. Santhanam ◽  
Y. Krishna ◽  
M. S. Sivakumar
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Shape Recovery ◽  
Scanning Calorimetry ◽  
Helical Springs ◽  
Heating And Cooling ◽  
Niti Sma ◽  
Different Temperatures ◽  
Sma Spring ◽  
Sma Helical Spring

Shape memory alloys (SMAs) are one of the most widely used smart materials in many applications because of their shape memory effect property. In this work, the behaviour of NiTi SMA helical spring was evaluated through isothermal force-displacement experiment (IFDE) and shape recovery force experiment (SRFE). The transformation temperatures of SMA spring were determined by differential scanning calorimetry (DSC) test. In situ heating of SMA spring by direct electric current was used instead of conventional furnace heating. The continuous measurement of temperature of SMA spring during heating and cooling was ensured with attaching the thermocouple by heat shrinkable sleeve. From IFDE, the force-deflection behaviour under different constant temperatures and from SRFE and the force-temperature behaviour under different constant deflections are obtained. The results of IFDE show that the force increases and the residual displacement decreases with an increase in the temperature, and the stiffness of the spring at austenite state is greater than that at martensitic state. The results of SRFE show that the shape recovery force increases more or less linearly with an increase in the initial deflection for the same temperature range. But the shape recovery forces are not similar during heating and cooling stages. This paper presents the experimental setup, experimental procedures, and the observed behaviour of SMA helical springs under different temperatures and deflections.

A review of rotary actuators based on shape memory alloys

2017 ◽  
Vol 28 (14) ◽  
pp. 1863-1885 ◽  
Author(s):  
Han Yuan ◽  
Jean–Christophe Fauroux ◽  
Frédéric Chapelle ◽  
Xavier Balandraud
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Cooling System ◽  
Engineering Applications ◽  
Heating And Cooling ◽  
Output Torque ◽  
The Future ◽  
New Applications

The development of rotary actuators is an important aspect of the engineering applications of shape memory alloys. This article reviews about a hundred references on this topic, and presents around eighty actuators driven by shape memory alloys. A classification is made according to the type of rotation (continuous or non-continuous, single or reversible direction). Different factors are then discussed, such as the characteristics of the shape memory alloy elements, the heating and cooling system for the shape memory alloy, the control of the actuator, and the output torque and stroke which can be attained. This article provides the first review focused on rotary actuators triggered by shape memory alloys, highlighting the specificities and potentialities of such actuators for new applications in the future.

Shape Memory Alloy Springs Used as Reduced Power/Weight Actuators

Aerospace ◽  
2004 ◽  
Author(s):  
Gareth Knowles ◽  
Ross Bird ◽  
Victor Birman
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Flight Control ◽  
Austenitic Phase ◽  
Numerical Predictions ◽  
Coil Diameter ◽  
Sma Spring ◽  
Sma Helical Spring ◽  
Reduced Power Consumption ◽  
Air Vehicles

The paper presents a concept and realization of using shape memory alloy (SMA) spring actuators for deployment of flight control surfaces of small air vehicles. These actuators replace heavy servomotors resulting in increased endurance of the vehicle as well as reduced power consumption. The actuator represents a spiral wound tubular SMA helical spring that is extended in its martensitic phase prior to actuation. The actuation can be achieved by directing exhaust gas from the onboard engine, i.e. providing an influx of heat. When activated, the spring returns to its original (compressed) shape generating a force in the range of 10 to 25 lbf. The advantage of using SMA springs is related to the enhanced stiffness after activation, as the material transforms from the martensitic to austenitic phase. Such added rigidity is useful to deploy telescoping wing surfaces and implement extensive geometric airframe changes. Numerical examples conducted with a typical spring material and geometry illustrated that the required stroke can be achieved with the spring index of about 10, coil diameter of 2.5 inches and SMA diameter in the range from 0.14 to 0.24 inches. Experimental data confirms these numerical predictions. The present study has proven the feasibility of using SMA actuators for the deployment of wing surfaces of small air vehicles.

Enhancing the actuation frequency of shape memory alloy wire by vibration-enhanced cooling

2019 ◽  
Vol 30 (20) ◽  
pp. 3177-3189 ◽  
Author(s):  
Brent Utter
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Heating Time ◽  
Shape Memory Alloy Wire ◽  
High Current ◽  
Frequency Increase ◽  
Actuation Frequency ◽  
Alloy Wire ◽  
Heating And Cooling ◽  
Novel Approach

Shape memory alloy wire actuators are lightweight, compact, and have high actuation stress, but their actuation frequency is limited by the rate they can be thermally cycled. Heating time can be reduced with high current, but rapidly cooling the material without introducing disadvantages is a challenge. This study establishes the feasibility of a novel approach to more rapidly cool shape memory alloy wires based on inducing their first mode of vibration. To achieve this, a steel spring pin placed on the wire was driven by an electromagnet as the shape memory alloy cooled. Experiments were conducted with a shape memory alloy wire (250 mm length, 0.381 mm diameter, 70°C austenite finish temperature) that was thermally cycled against constant forces and against an extension spring. The heating and cooling times were measured for the vibrating and non-vibrating trials to determine the factor of actuation frequency increase, which ranged from 1.55 to 2.10. A model of cooling time was developed and compared with the experimental results, with percent errors ranging from 5.3% to 32.8%. The approach was demonstrated in an application: a shape memory alloy–driven rotary ratcheting mechanism, with which factors of actuation frequency increase greater than 1.80 were measured due to vibration-enhanced cooling.

scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

Thermal performance of a radiant wall heating and cooling system with pipes attached to thermally insulating bricks

2021 ◽  
pp. 111122
Author(s):  
Michal Krajčík ◽  
Martin Šimko ◽  
Ondřej Šikula ◽  
Daniel Szabó ◽  
Dušan Petráš
Keyword(s):  
Thermal Performance ◽  
Cooling System ◽  
Heating And Cooling ◽  
Wall Heating

scholarly journals WattScale

2021 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
Srinivasan Iyengar ◽  
Stephen Lee ◽  
David Irwin ◽  
Prashant Shenoy ◽  
Benjamin Weil
Keyword(s):  
Cooling System ◽  
Large Population ◽  
Ground Truth ◽  
Detection Algorithm ◽  
Building Envelope ◽  
Ground Truth Data ◽  
Heating And Cooling ◽  
Data Driven Approach ◽  
Execution Mode ◽  
The Individual

Buildings consume over 40% of the total energy in modern societies, and improving their energy efficiency can significantly reduce our energy footprint. In this article, we present WattScale, a data-driven approach to identify the least energy-efficient buildings from a large population of buildings in a city or a region. Unlike previous methods such as least-squares that use point estimates, WattScale uses Bayesian inference to capture the stochasticity in the daily energy usage by estimating the distribution of parameters that affect a building. Further, it compares them with similar homes in a given population. WattScale also incorporates a fault detection algorithm to identify the underlying causes of energy inefficiency. We validate our approach using ground truth data from different geographical locations, which showcases its applicability in various settings. WattScale has two execution modes—(i) individual and (ii) region-based, which we highlight using two case studies. For the individual execution mode, we present results from a city containing >10,000 buildings and show that more than half of the buildings are inefficient in one way or another indicating a significant potential from energy improvement measures. Additionally, we provide probable cause of inefficiency and find that 41%, 23.73%, and 0.51% homes have poor building envelope, heating, and cooling system faults, respectively. For the region-based execution mode, we show that WattScale can be extended to millions of homes in the U.S. due to the recent availability of representative energy datasets.

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