MEMORY SHAPE ALLOY Shape Memory Alloy module - Title Page

Definisi Shape Memory Alloy (SMA) Shape Memory Alloys (SMAs) merupakan kelompok paduan logam yang dapat menemukan kembali dengan baik regangan permanennya bila dipanaskan pada suhu tertentu.

Sejarah SMA Ditemukan tahun 1932, Oleh Chang dan Read. Tahun 1938, kuningan (CuZn). Tahun 1951, Emas kadmium (AuCd). Tidak ada aktivitas sampai 1962. Buehler and co-workers menemukan Nickel-Titanium (NiTi).

Apa material shape memory ?

Prinsip dasar SMA mempunyai dua fase stabil – fase suhu tinggi ( austenite) dan fase suhu rendah (martensite). Martensite dapat muncul dalam dua bentuk yaitu twinned dan detwinned. Fase transisi yang muncul antara dua fase di atas ( melalui pemanasan/pendinginan) merupakan dasar untuk menjelaskan sifat unik SMA.

Shape Memory Alloys? Austenite Martensite 4/9/2017 Shape Memory Alloys? Shape Memory Alloys (SMAs) merupakan paduan logam yang mengalami transisi fase padat –padat dan dapat menunjukkan kembali regangannya. contoh: Nitinol Austenite High temperature phase Cubic Crystal Structure Martensite Low temperature phase Monoclinic Crystal Structure This is a representation of the transformation process. The amount of heat needed depends on the material’s transformation temperature. This can be room temperature or freezing. Twinned Martensite Detwinned Martensite

Induksi termal pada fase transisi SMA Mf Ms As Af Austenite Martensite TEMPERATURE (twinned) Characteristic temperatures: Mf=Martensitic Finish Ms=Martensitic Start As=Austenitic Start Af=Austenitic Finish

Efek Shape Memory : Stress Free Shape Recovery Detwinned Martensite (stressed - deformed) Detwinned Martensite (stressed - deformed) STRESS STRESS Twinned Martensite (unstressed) Mf Ms As Af Mf Ms As Af Detwinned Martensite (unstressed - deformed) Austenite (undeformed) TEMPERATURE TEMPERATURE

Efek shape memory (SME)?

4/9/2017 Efek Shape Memory s Detwinning e Cooling Heating/Recovery T

Shape Memory Effect: Shape Recovery Under Stress Detwinned Martensite (stressed) Austenite M M A A f s s f TEMPERATURE

The Pseudoelastic Effect TEMPERATURE M f s A Austenite Detwinned Martensite (stressed) STRESS

Aplikasi Nanomuscles Alat-alat bedah Tissue Spreader Stents (angioplasty) Coronary Probe Brain Spatula Endoscopy: miniature zoom device, bending actuator Force sensor Smart skin (wing turbulence reduction)

SMAs in Bio-medical Devices

Aplikasi... Otot logam yang lentur dengan suhu rendah Penguapan dan kondensasi platina murni pada gas atmosfir tipis akan terkonversi menjadi partikel lebih kecil 5 nanometer. Partikel-partikel ini dimampatkan dalam tubuh nanoporous. Padatan yang diperoleh selanjutnya dicelupkan ke cairan konduktif (electrolyte) dan mengisi rongga. Melalui elektrolit ini , asam atau basa yang bermuatan listrik dapat dibawa oleh nanopartikel ke padatan.

Aplikasi ... Tegangan listrik menyebabkan muatan elektrolit berubah. Muatan listrik akan menginduksi permukaan nanopartikel. Perubahan muatan ini membuat perubahan konduksi elektron atom . http://www.fzk.de/stellent/groups/public/documents

Nanomuscles

Discussion of Application An advantage to this new shape memory alloy is its’ efficiency. No other alloy or polymer can compare to its’ strength and efficiency to weight ratio. Nanomuscles weigh just one gram but can lift 140 grams, and are preferred to electric motors as they are far cheaper to produce.

SHAPE MEMORY ALLOY–NITINOL What is it? One type of shape memory alloy is Nitinol, which is short for Nickel Titanium Naval Ordnance Laboratory and which acknowledges the site of its discovery in 1965 Where does it get its name? Nitinol is an alloy of about 56 % Nickel and 44 % Titanium. (Hence the name: Ni–Ti–Naval Ordinance Laboratory) What does it do? Nitinol “remembers” its original shape and springs back up to temperatures up to 500 degrees C. Can be strained 8 to 10 times more than spring steel without permanent deformation. Won’t kink. Coils easily.

HOW DOES NITINOL WORK? Nitinol is made of Nickel and Titanium Most solids have one crystal structure, but Nitinol has two The crystal structure is different at cold and hot temperatures At cold temps it is soft and easy to bend but at hot temps it is stiff and springy. Nitinol is made up of two kinds of atoms: Nickel atoms and Titanium atoms. They are arranged in an organized pattern called a crystal structure. Most solids have a crystal structure, but Nitinol is special because it has two different crystal structures, also called solid phases. At colder temperatures, Nitinol’s atoms are in one arrangement, called martensite. At higher temperatures, Nitinol’s atoms are in a slightly different crystal structure, called austenite. When you heat Nitinol, you give the atoms energy to move from the martensite structure to the austenite structure, and as it cools back down, they move back. The atoms in the Nitinol move just a little bit, but this makes a huge difference in how the metal feels and behaves. At lower temperatures, Nitinol is soft and easy to bend. At hotter temperatures, it is stiff and springy.

WHY IS NITINOL SO VERSATILE? It has similar properties to human hair and human tendons and is being used in a wide range of applications. Nitinol is sometimes referred to as the Shape shifter of the 21st century. The reason –it mimics human tendons and human hair which has made them useful in a lot of inventions, like wires for braces, staples that hold broken bones together, coffee pots that turn off when the water is hot enough, and trick spoons that bend when you try to stir your tea!, Medical components, Space components, Textiles, robotics, Water sprinklers, Pipe connections This SMART property has made them useful in many inventions like wires for braces, staples that hold broken bones together, coffee pots that turn off when the water is hot enough trick spoons that bend when you try to stir your tea

Did You Know? THAT YOU CAN NOW HAVE… Nitinol’s amazing properties allows surgeons to perform life saving operations Ninol is used to: Seal holes in the heart Patch up faulty blood vessels Attach tendons to bones. AMPLATZER® Septal Occluder for heart defect repair utilizes the shape memory of Nitinol

Research scientists, innovators and artists are always finding new creative uses for Nitinol. Knee replacements Spectacle frames Medical stents Repair broken bones Replace damaged discs. What else?

Applications Of Nitinol THE ICEMOBILE A Nitinol heat engine, called the Icemobile has a loop of Nitinol which you immerse in warm water, to make it spin (which then cuts up ice cubes). Here are some applications where Nitinol has been used. PURPOSE: To illustrate shape-memory alloy. DESCRIPTION: A thin NITINOL wire loop is connected around two pulleys. The lower pulley is placed half way into the water at 35-40 degrees celcius and an ice cube gently touched to the wire. If the wire is gently spun downward through the ice cube into the water bath, it will continue to spin, cutting the ice cube in two. Alternatively, a glob of crushed ice placed around the wire as it enters the box will cause the wire to circulate as described above, as shown in the photograph. SUGGESTIONS: Do not bend or stress wire or the memory may be changed. If ice forms on the wire, melt it by immersing the wire in the water. REFERENCES: (PIRA 4F30.60) EQUIPMENT: Icemobile ice cutter assembly, beaker of warm water, ice cubes, dial thermometer. SETUP TIME: 5 min.