384
K. Bo et al.
An important damage monitoring technique for composite pressure vessel was
acoustic emission (AE). In the application of composite materials for AE technique,
many of the researches involving AE monitoring had concentrated on the understanding and differentiating the failure processes, prediction of residual strength, the
extent of damage and damage location [4]. Many studies were performed into the
AE analysis of carbon fiber and glass fiber composites [5, 6]. Lin et al. [7] explored
the thermo-mechanical properties under hydraulic and atmospheric fatigue cycling
by using AE technique. Mohammadi et al. [8] evaluated damage under impact loads
in composite structures. But few studies were involved in detecting impact damage
and their accumulation in different cycle times by AE testing on type 4 cylinders.
In this paper, a study involving AE testing was conducted to a type 4 cylinder
with artificial impact damage. Impact damage of cylinder accumulated gradually
with increasing of cycle times, which changed the safety performance and condition
of the cylinder. AE testing was performed on the cylinder after different cycle times to
determine that wether it can be used to assess the extent of impact damage. Different
parameters of AE signals collected were discussed and analyzed in details. The
conclusion of our study can provide an experimental basis for type 4 cylinder impact
damage evaluation.
33.2 Experiment Program
The overall process of experiment designed was as follows:
(1) Prefabricated an impact damage in a type 4 cylinder.
(2) Cycled the cylinder from 0.2 MPa to working pressure.
(3) After a certain number of cycle times, detected the cylinder by AE testing.
(4) Repeated operation of cycle and AE testing until the cylinder was cycled to
failure.
33.2.1 Details of the Cylinder in the Test
A fully-wrapped glass fiber composite gas cylinder with non-metallic liner designed
for filling LPG was used in the test, which dimension was 290 × 440 mm (D ×
L), capacity of 18L. The working pressure was 2.1 MPa. Impact damage was made
as enterprise standards QB101-2017 Fully-wrapped Composite Gas Cylinder with
Non-metallic Liner. Cylinder was filled with water until its weight was the same as
filling weight with LPG (7.56 kg). Then the cylinder was dropped to a punch from a
height of 1.2 m. Drop test was shown in Figs. 33.1 and 33.2a. This operation caused
a impact damage with a length of about 100 mm in cylindrical portion and dome
region of the cylinder. Its appearance was shown in Fig. 33.2a.
K. Bo et al.
An important damage monitoring technique for composite pressure vessel was
acoustic emission (AE). In the application of composite materials for AE technique,
many of the researches involving AE monitoring had concentrated on the understanding and differentiating the failure processes, prediction of residual strength, the
extent of damage and damage location [4]. Many studies were performed into the
AE analysis of carbon fiber and glass fiber composites [5, 6]. Lin et al. [7] explored
the thermo-mechanical properties under hydraulic and atmospheric fatigue cycling
by using AE technique. Mohammadi et al. [8] evaluated damage under impact loads
in composite structures. But few studies were involved in detecting impact damage
and their accumulation in different cycle times by AE testing on type 4 cylinders.
In this paper, a study involving AE testing was conducted to a type 4 cylinder
with artificial impact damage. Impact damage of cylinder accumulated gradually
with increasing of cycle times, which changed the safety performance and condition
of the cylinder. AE testing was performed on the cylinder after different cycle times to
determine that wether it can be used to assess the extent of impact damage. Different
parameters of AE signals collected were discussed and analyzed in details. The
conclusion of our study can provide an experimental basis for type 4 cylinder impact
damage evaluation.
33.2 Experiment Program
The overall process of experiment designed was as follows:
(1) Prefabricated an impact damage in a type 4 cylinder.
(2) Cycled the cylinder from 0.2 MPa to working pressure.
(3) After a certain number of cycle times, detected the cylinder by AE testing.
(4) Repeated operation of cycle and AE testing until the cylinder was cycled to
failure.
33.2.1 Details of the Cylinder in the Test
A fully-wrapped glass fiber composite gas cylinder with non-metallic liner designed
for filling LPG was used in the test, which dimension was 290 × 440 mm (D ×
L), capacity of 18L. The working pressure was 2.1 MPa. Impact damage was made
as enterprise standards QB101-2017 Fully-wrapped Composite Gas Cylinder with
Non-metallic Liner. Cylinder was filled with water until its weight was the same as
filling weight with LPG (7.56 kg). Then the cylinder was dropped to a punch from a
height of 1.2 m. Drop test was shown in Figs. 33.1 and 33.2a. This operation caused
a impact damage with a length of about 100 mm in cylindrical portion and dome
region of the cylinder. Its appearance was shown in Fig. 33.2a.