24 Experiment Research on Tensile Process …
293
24.4.3 Discussion on Generation Mechanism of Acoustic
Emission Signal
At different stages in the sample tensile process, the distribution of the characteristic
parameters of the acoustic emission signal is very different.
In the elastic phase, the acoustic emission source is active, showing that the amplitude of the acoustic emission signal is small and the energy is low. The signal is
basically at the beginning of the stretching, and it is inferred that it is the noise signal
generated by the loading end when loading begins.
In the yield stage (ascending section), the acoustic emission source is active,
which is manifested by a larger amplitude and higher energy of the acoustic emission
signal. The signals are all located in the transition stage from the elastic stage to the
yield stage. The generation mechanism is the internal segment of HDPE material
(amorphous) Area) movement began to increase.
During the yield stage (descent), the source of acoustic emission is inactive.
In the first half of plastic deformation, the acoustic emission source is active,
showing that the amplitude of the acoustic emission signal is large and the energy
is high. The entire plastic deformation signal is concentrated in this stage, and the
signal slowly increases at the beginning of plastic deformation. The signal amount
reaches the maximum at Mid-term. The mechanism is that during the deformation
of the thin neck, the orientation of the microcrystalline macromolecular structure
begins to change, the order of the crystallites in the HDPE material in the early stage
of the narrow neck changes is little, and the acoustic emission source is inactive.
In the mid-term, as the crystallites began to occur large-scale slippage and other
deformations, the degree of change in orderness was large.
In the second half of plastic deformation, the acoustic emission signal is inactive;
as the change value of the order of crystallites decreases, the activity of the acoustic
emission source decreases, and the signal is low;
During the fracture stage, the acoustic emission signal is active, which is manifested by the large amplitude and high energy of the acoustic emission signal, which
is mainly the signal generated by the sample fracture.
24.5 Conclusion
1. HDPE materials produce acoustic emission signals during deformation and fracture, indicating that it is feasible to detect HDPE materials by acoustic emission
methods;
2. The frequency of HDPE’s acoustic emission signal is between 70–260 kHz, and
VS150 resonant sensor can be used for the detection and monitoring of this
material;
293
24.4.3 Discussion on Generation Mechanism of Acoustic
Emission Signal
At different stages in the sample tensile process, the distribution of the characteristic
parameters of the acoustic emission signal is very different.
In the elastic phase, the acoustic emission source is active, showing that the amplitude of the acoustic emission signal is small and the energy is low. The signal is
basically at the beginning of the stretching, and it is inferred that it is the noise signal
generated by the loading end when loading begins.
In the yield stage (ascending section), the acoustic emission source is active,
which is manifested by a larger amplitude and higher energy of the acoustic emission
signal. The signals are all located in the transition stage from the elastic stage to the
yield stage. The generation mechanism is the internal segment of HDPE material
(amorphous) Area) movement began to increase.
During the yield stage (descent), the source of acoustic emission is inactive.
In the first half of plastic deformation, the acoustic emission source is active,
showing that the amplitude of the acoustic emission signal is large and the energy
is high. The entire plastic deformation signal is concentrated in this stage, and the
signal slowly increases at the beginning of plastic deformation. The signal amount
reaches the maximum at Mid-term. The mechanism is that during the deformation
of the thin neck, the orientation of the microcrystalline macromolecular structure
begins to change, the order of the crystallites in the HDPE material in the early stage
of the narrow neck changes is little, and the acoustic emission source is inactive.
In the mid-term, as the crystallites began to occur large-scale slippage and other
deformations, the degree of change in orderness was large.
In the second half of plastic deformation, the acoustic emission signal is inactive;
as the change value of the order of crystallites decreases, the activity of the acoustic
emission source decreases, and the signal is low;
During the fracture stage, the acoustic emission signal is active, which is manifested by the large amplitude and high energy of the acoustic emission signal, which
is mainly the signal generated by the sample fracture.
24.5 Conclusion
1. HDPE materials produce acoustic emission signals during deformation and fracture, indicating that it is feasible to detect HDPE materials by acoustic emission
methods;
2. The frequency of HDPE’s acoustic emission signal is between 70–260 kHz, and
VS150 resonant sensor can be used for the detection and monitoring of this
material;