Application of New Type Gold Material in Automotive Water Body Constructor

Shape memory alloy characteristics

In addition to the strength, stiffness, ductility, ductility, and conductivity of metals, shape memory alloys also have very peculiar shape memory effects, superelasticity, and high damping properties. The alloy is a thermoelastic martensitic transformation alloy, and its phase transformation is reversible. The shape memory effect of the alloy is produced during the martensitic transformation.

Typical shape memory alloys are nickel-titanium alloys, in addition to copper-zinc-aluminum and copper-aluminum-antimony. Nickel-titanium (Ti50Ni50) alloy is one of the most practical shape memory alloys. Its martensitic transformation point is about 40°C, and it is convenient to use. Adding the third element can make the martensite transformation point reach 100°C. Its tensile strength is 636 MPa, pseudoelastic deformation is 10%, and it is generally practical in the range of 2% 3%. And reflect the influence of reheat rate and pre-deformation on the restoring force of nickel-titanium alloy (force to restore the original shape). It can be seen that the higher the temperature and the higher the heating rate, the greater the initial deformation and the greater the restoring force.

Nickel-titanium alloy's recovery force and regenerative speed relationship 400 300 200 100 300 320 340 360 380 Temperature T/K 100 k/s 35 k/s 15 k/s Recovery pressure/MPa refers to the memory alloy with its high temperature mother Phase (A) (Cscl structure) shape characteristics, TiNi memory alloy SME characteristics: deformation in the low-temperature M state, the residual strain disappears after heating, the alloy returns to the shape of the pre-deformation A state can reverse the stress-strain effect, when the alloy is free In the state, this effect can be used to output strain to the outside. When the alloy is in the constraint state, the stress can be output to the outside. As shown.

Relationship between restoring force and pre-deformation of nickel-titanium alloy Shape memory SE refers to the phenomenon that the memory alloy in the A state produces a strain that is much larger than its elastic limit strain under external force, and the strain can be automatically recovered after unloading. If the alloy exceeds the elastic limit stress under the temperature condition above Af, a large amount of plastic deformation occurs in the shape of the alloy (the elongation rate thereof is up to 10% or more) and stress induced martensite is generated. It is stable under the action of stress. Once the stress is eliminated, the martensite reverse phase transformation occurs immediately, and it returns to the state of the mother phase. The macroscopic deformation under the action of stress also disappears completely with the reverse phase transformation and returns to its original state. The stress-strain relationship is nonlinear, which is the superelasticity of the alloy. As shown.

The use of shape memory alloys in the application of TiNi shape memory alloys mainly utilizes the shape memory effect (SME) and superelasticity (SE) of the shape memory alloy and its derived damping effect. TiNi shape memory alloys are wire, plate, and spring. Components such as tubes, tubes, nails, and rings are gradually used in aerospace vehicles, space structure platforms, nuclear reactors, building bridges, and marine structures to control the deformation or vibration of structures, and to monitor the stress, strain, temperature, and damage inside structures. Such conditions improve the safety and reliability of the engineering structure.

The automobile thermostat automatically adjusts the amount of water entering the radiator according to the level of the cooling water temperature and changes the circulation range of the water to adjust the cooling capacity of the cooling system to ensure that the engine operates within a suitable temperature range. In the prior art, automotive thermostats are controlled using thermal expansion and shrinkage of paraffin. When the water temperature is lower than 70°C, the thermostatic expansion tube is in a contracted state and the main valve is closed. When the water temperature is higher than 80°C, the expansion tube expands, the main valve gradually opens, and the circulating water in the radiator begins to flow. The thermostat must maintain a good technical state, otherwise it will seriously affect the normal operation of the engine. If the temperature controller's main valve is opened too late, it will cause the engine to overheat; if the main valve is opened too early, the engine warm-up time will be prolonged and the engine temperature will be too low.