Research On SMA's Mechanical Property And Its Application On Fan Clutch

Some plastic deforming material can return their former shape by suitable heat. That phenomenon is called Shape Memory Effect (SME). The metal with SME generally is composed of more than two metal elements, so is called Shape Memory Alloy (SMA). Beside its SME, SMA has some special dynamic behaviors such as pseudoelasticity and ferroelasticity. SMA's particular properties have been receiving increasing attention in recent years, and are extensively used in many fields, such as aviation, national defense, medical devices and automobile, etc.SMA can be used universally in automobile, such as radiator, tire, engine and fan clutch. The leak of oil exists in traditional silicon-oil fan clutch during driving. And SMA is used to design a new fan clutch can solve the problem.The research way of the paper is that a new fan clutch is designed based on SMA's microstructures and its constitutive model, according to the work of fan clutch.The main work in this dissertation are as follows:1) SMA's microstructures are analyzed, and the properties of martensite and austenite are studied.2) The SMA's memory function is researched when the temperature changed, and the property of its drive is studied, too.3) Based on thermodynamics and microscopic mechanics, the constitutive model of SMA is established, and mutual relationships between the content of martensite, coefficient, elastic modulus, stress, strain and temperature are analyzed.4) The deliver equation is established controlled by the temperature, and the equation provides theoretical foundation for the design of fan clutch.5) SMA's coil spring used in fan clutch is designed and calculated.In this dissertation the contributions are summarizede as follows:1) A two-phase constitutive model is established and SMA's themal mechanisms are introduced.2) The deliver equation controlled by the temperature is established, which provides theoretical foundation for the design of fan clutch.