BY SYNDICATE NO 2

INTRODUCTION WHAT ARE SHAPE MEMORY ALLOYS. MATERIALS WHICH REMEMBERS ITS SHAPE. COMMONLY KNOWN AS SMA. AFTER IT IS DEFORMED, IT REGAINS ITS ORIGINAL GEOMETRY BY ITSELF DURING HEATING (ONE-WAY EFFECT) OR, AT HIGHER AMBIENT TEMPERATURES, SIMPLY DURING UNLOADING (PSEUDO-ELASTICITY). RAPIDLY FINDING ITS PLACE IN MOST OF THE INDUSTRIES. FURTHERANCE OF PHASE TRANSFORMATION KNOWLEDGE.

PHASES PH 1 : BRIEF ON SMA. PH 2 : THEORY BEHIND SMA. PH 3 : SHAPE MEMORY EFFECT & PSEUDO- ELASTICITY. PH 4 : APPLICATIONS OF SMA. CONCLUSION.

BRIEF ON SMA METALS THAT REMEMBER ITS ORIGINAL SHAPE. EXHIBIT TWO UNIQUE PROPERTIES :- PSEUDO-ELASTICITY. SHAPE MEMORY EFFECT. ARNE OLANDER FIRST OBSERVED THESE UNUSUAL PROPERTIES IN 1938, BUT NOT UNTIL THE 1960'S WERE ANY SERIOUS RESEARCH ADVANCES MADE IN THE FIELD OF SHAPE MEMORY ALLOYS.

BRIEF ON SMA DIVERSE APPLICATIONS MADE THEM INCREASINGLY IMP & VISIBLE TO THE WORLD. NITINOL OR NICKEL-TITANIUM ALLOY MOST IMP. NITINOL IS Ni-Ti NAVAL ORD LABARATORY. SHAPE MEMORY PROPERTY OF NITINOL WAS DISCOVERED BY ACCIDENT. AT A LABORATORY MANAGEMENT MEETING, A STRIP OF NITINOL WAS PRESENTED THAT WAS BENT OUT OF SHAPE MANY TIMES. ONE OF THE PEOPLE PRESENT, DR. DAVID S. MUZZEY, HEATED IT WITH HIS PIPE LIGHTER, AND SURPRISINGLY, THE STRIP STRETCHED BACK TO ITS ORIGINAL FORM.

THEORY BEHIND SMA HOW DOES SMA “REMEMBERS” ITS SHAPE WAS THE QUESTION AFTER ITS DISCOVERY. THIS OCCURS DUE TO SOLID STATE PHASE CHANGE. TYPICALLY WHEN ONE THINKS OF A PHASE CHANGE A SOLID TO LIQUID OR LIQUID TO GAS CHANGE IS THE FIRST IDEA THAT COMES TO MIND. A SOLID STATE PHASE CHANGE IS SIMILAR IN THAT A MOLECULAR REARRANGEMENT IS OCCURRING, BUT THE MOLECULES REMAIN CLOSELY PACKED SO THAT THE SUBSTANCE REMAINS A SOLID. PHASES INVOLVED ARE AUSTENITE AND MARTENSITE.

THEORY BEHIND SMA INVOLVES THE REARRANGEMENT OF THE POSITION OF PARTICLES WITHIN THE CRYSTAL STRUCTURE OF THE SOLID. TRANSITION TEMP OF THESE PHASES IS VERY LOW. THE TRANSITION TEMPERATURE VARIES FOR DIFFERENT COMPOSITIONS FROM ABOUT -50 ° C TO 166 ° C. BELOW TRANSITION TEMP IS MARTENSITE AND ABOVE IT IS AUSTENITE. IN THE MARTENSITE PHASE, NITINOL CAN BE BENT INTO VARIOUS SHAPES.

THEORY BEHIND SMA TO FIX THE "PARENT SHAPE" (AS IT IS CALLED), THE METAL MUST BE HELD IN POSITION AND HEATED TO ABOUT 500 ° C. THE HIGH TEMPERATURE CAUSES THE ATOMS TO ARRANGE THEMSELVES INTO THE MOST COMPACT AND REGULAR PATTERN POSSIBLE RESULTING IN A RIGID CUBIC ARRANGEMENT KNOWN AS THE AUSTENITE PHASE. ABOVE THE TRANSITION TEMPERATURE, NITINOL REVERTS FROM THE MARTENSITE TO THE AUSTENITE PHASE WHICH CHANGES IT BACK INTO ITS PARENT SHAPE. THIS CYCLE CAN BE REPEATED MILLIONS OF TIMES.

SHAPE MEMORY EFFECT TRANSITION TEMP DEPENDS UPON THE COMPOSITION OF THE ALLOY. THE TEMPERATURES AT WHICH EACH OF THESE PHASES BEGIN AND FINISH FORMING ARE REPRESENTED BY VARIABLES : MS, MF, AS, AF. MS & MF ARE START & FINISH TEMP OF AUSTENITE TO MARTENSITE TRANSFORMATION. AS, AF ARE START & FINISH TEMP OF MARTENSITE TO AUSTENITE TRANSFORMATION. WHEN THE ALLOY IS COOLED BELOW THE TRANSITION TEMP IT TAKES THE TWINNED MARTENSITE STRUCTURE.

SHAPE MEMORY EFFECT HAS SAME SHAPE AND SIZE AS AUSTENITE SO NO VISIBLE DIFFERENCE OBSERVED UNLESS ITS DEFORMED/LOADED WHEN DEFORMED IT TAKES THE DESIRED SHAPE IF ALLOY HEATED ABOVE TRANSITION TEMP; TAKES THE PREVIOUS SHAPE IN AUSTENITE STRUCTURE

SHAPE MEMORY EFFECT

SHAPE MEMORY EFFECT

SHAPE MEMORY EFFECT

PSEUDO-ELASTICITY PSEUDO-ELASTICITY OCCURS IN SHAPE MEMORY ALLOYS WHEN THE ALLOY IS COMPLETELY COMPOSED OF AUSTENITE. UNLIKE THE SHAPE MEMORY EFFECT, PSEUDO- ELASTICITY OCCURS WITHOUT A CHANGE IN TEMPERATURE.

PSEUDO-ELASTICITY THE LOAD ON THE SHAPE MEMORY ALLOY IS INCREASED UNTIL THE AUSTENITE BECOMES TRANSFORMED INTO MARTENSITE SIMPLY DUE TO THE LOADING. THE LOADING IS ABSORBED BY THE SOFTER MARTENSITE, BUT AS SOON AS THE LOADING IS DECREASED THE MARTENSITE BEGINS TO TRANSFORM BACK TO AUSTENITE SINCE THE TEMPERATURE OF THE WIRE IS STILL ABOVE AF, AND THE WIRE SPRINGS BACK TO ITS ORIGINAL SHAPE.

Load Diagram of the pseudo-elastic effect Occurring PSEUDO-ELASTICITY Load Diagram of the pseudo-elastic effect Occurring

PSEUDO-ELASTICITY

APPLICATIONS OF SMA AERONAUTICAL APPLICATIONS. AIRCRAFT MANEUVERABILITY DEPENDS HEAVILY ON THE MOVEMENT OF FLAPS FOUND AT THE REAR OR TRAILING EDGE OF THE WINGS. MOST AIRCRAFT IN THE AIR TODAY OPERATE THESE FLAPS USING EXTENSIVE HYDRAULIC SYSTEMS. THIS COMPLEX SYSTEM OF PUMPS AND LINES IS OFTEN RELATIVELY DIFFICULT AND COSTLY TO MAINTAIN.

APPLICATIONS OF SMA AERONAUTICAL APPLICATIONS. THE SHAPE MEMORY WIRE IS USED TO MANIPULATE A FLEXIBLE WING SURFACE. THE SHAPE MEMORY EFFECT IS INDUCED IN THE WIRES SIMPLY BY HEATING THEM WITH AN ELECTRIC CURRENT, WHICH IS EASILY SUPPLIED THROUGH ELECTRICAL WIRING, ELIMINATING THE NEED FOR LARGE HYDRAULIC LINES.

Hinge less shape memory alloy Flap APPLICATIONS OF SMA Typical Wing and Flap Hinge less shape memory alloy Flap

APPLICATIONS OF SMA MEDICAL APPLICATIONS REPAIRING FRACTURES ORTHODONTIC TREATMENTS TWEEZERS MUSCLE WIRES IN ROBOTICS INDUSTRY FIRE SPRINKLERS FUTURE APPLICATIONS USE OF MECH ENERGY FROM SHAPE TRANSFORMATION IN CAR ENGINES ENGINE COOLING LUBRICATION CONTROL CONTROL OF RADIATOR BLIND

APPLICATIONS OF SMA TYPICAL OSTEOSYNTHESIS TOOLS CONVENTIONAL BONE PLATE USED TO REPAIR JAW FRACTURE TYPICAL OSTEOSYNTHESIS TOOLS

EVEN A BADLY FRACTURED FACE CAN BE RECONSTRUCTED USING BONE PLATES APPLICATIONS OF SMA EVEN A BADLY FRACTURED FACE CAN BE RECONSTRUCTED USING BONE PLATES

USE OF SMA IN ROBOTICS INDUSTRY APPLICATIONS OF SMA USE OF SMA IN ROBOTICS INDUSTRY

APPLICATIONS OF SMA

CONCLUSION USES & APPLICATION ENSURE BRIGHT FUTURE OF THESE ALLOYS RESEARCH AT ROBOTICS & MAT SC DEPARTMENTS ALL OVER THE WORLD INNOVATIVE IDEAS FOR USING SMA USE OF SMA IN VAST NO OF FIELDS ENSURES IT PROMISING FUTURE.

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