Low Velocity Impact on Cylindrical Composite Pressure Vessels Study

This report investigates the deformation and burst pressure of cylindrical composite pressure vessels subjected to low-velocity impact using finite element analysis and ANSYS software. The study examines the failure progression leading to bursting, considering factors such as material properties, impact velocity, and boundary conditions. A cylindrical vessel made of high-density polyethylene (HDPE) covered by fiberglass was analyzed, and the results indicated that transverse stresses in the innermost layer significantly contributed to material failure. The analysis confirmed that low-velocity impact damages the hoop layers, reducing the burst strength of the vessel. The study also models matrix cracks and validates the finite element method results using ANSYS, providing insights into improving the design and integrity of composite pressure vessels. Desklib offers similar reports and solved assignments for students.

ENGINEERING COMPUTATIONS AND SIMULATIONS
Name
Institution

Computation of Deformation and Burst Pressure of Cylindrical Composite Pressure Vessels
under Low Impact Velocity
Introduction
Composite materials have been widely used in the aerospace, machinery, shipping, and even the
construction industries due to their mechanical properties like high corrosion resistance, high
strength, high fatigue resistance, large damping, high stiffness and light weight (Matemilola and
Stronge, 2011, p. 2667). This property has made these materials specifically to be applicable in
the aerospace industry (Faggiani and Falzon, 2010, p. 741). Cylindrical composite pressure
vessels are however vulnerable to impact as it causes the material to deform and since they are
pressure vessels result in the vessel bursting at a certain pressure where the impact enhances
crack initiation, propagation and failure. This occurrence is associated with the fact that the
material has a low level of toughness which makes it brittle and thus easy for cracks to be
initiated, and propagated in the event of impact (Gong, Shim, and Toh, 2015, p.257).
Low velocity impact does not cause the crack development to be visible and this works to reduce
the burst strength of the vessel and thus increase the vulnerability of the vessels to accidents
Bursting of the cylindrical composite pressure vessels in the case of low velocity impact occurs
after deformation on the cylinder occurs. This deformation damages the fibers of the hoop layers
of the cylinder as induced compressive stresses which cause buckling whose intensity depends
on the material thickness. Other factors that are known to result in this buckling behavior include
the layup pattern of the hoop layers, the curvature of the material, the impact velocity and
resultant energy, the shape and size of the member impacting the pressure vessel and the
boundary conditions (Changliang, Mingfa, Wei, Haoran, 2016, p. 389).
Objective
This study considers a cylindrical composite pressure vessel that will be impacted on low
velocity using finite element analysis and the ansys software. The study enabled a
comprehension of failure progression to bursting in the material. The analysis will also entail the
evaluation of the burst pressure of the pressure vessel. The finite element method will be used to
conduct the structural assessment of the vessel while ansys will be used to model deformation

and analyze stresses around the point of impact and the mechanics of the damage resulting to
bursting.
Method
In this study, the stress distributions of composite pressure vessel were analyzed for a cylindrical
composite pressure vessel with the following boundary conditions. The internal vessel was made
of high-density polyethylene (HDPE) covered by fiberglass and the inner and the outer diameters
of the vessel are 114.5mm and 152.4 mm respectively. The length of the pressure vessel is 457.2
mm and the fibre orientation angles of the vessel are 90,+45 and -45 degrees
A 16mm hemispherical indentor was used to impact the pressure vessel on low velocity.

Hemispherical head
Cylindrical plate
V-Block support
Composite Cylinder

A 150mm long steel block were used to support the test specimens. The blocks had a shallow
angle V-groove of 145 degrees to support the cylinder at the cross section.
The data of force and displacement were recorded as the specimen was loaded and unloaded
during the experiment phase of the test at a loading rate of 2mm/min for all tests.
Internal Pressure Load and Boundary Conditions
Results
The number of elements considered in this study was 112479 and the number of nodes
considered was 647852. The value of the Tsai hill criterion was also computed in thus study in
order to assess how the cylindrical composite pressure vessel will fail under the boundary
conditions it was operation on. The stresses in the transverse direction and that of the fibers were
the largest in the innermost layer of the pressure vessel than in the other layers. The maximum
stress criterion of the scenario can also be utilized analyze stresses in the composite pressure
vessel system since the shear stresses obtained on impact are negligible. In this case failure
occurred because the stress experienced in the first layer of the fiber direction is much higher
than that was experienced in the transverse direction (Changliang, Mingfa, Wei, Haoran, 2016, p.

389). The transverse stress was also higher than the ultimate strength of the material thus causing
the material to failing the first layer. The results of the numerical analysis confirmed that the
failure had been caused by the stresses taking place in the transverse direction because it was
much greater than the ultimate strength of the material.
Deformation

Burst pressure analysis ansys model
Conclusion and Recommendations

This study involved the stress analysis of cylindrical composite pressure vessels using finite
element method and ansys in order to estimate the deformation and the burst pressure of the
vessel. Low velocity Impact and bursting tests were conducted. The damages noted on the
specimen affected the behavior of the material after low velocity impact and caused a reduction
in the burst strength of the vessel such that the 20MPa pressurized vessel with a material strength
of 70MPa had its hoop layers damaged by the low velocity impact of 15J by a 16mm impactor.
The specimen were observed to have matrix cracks that were also modeled in the stress analysis
models of the impact carried out using ansys. These can be explained by the differences in the
orientation of the fiber layers that are overwrapped on the vessel which when impacted decreased
the bending stiffness of the material as the impacting force deflects the material to cause
deformation and reduce stiffness (Kim, Lee, and Hwang, 2012, p. 2181). Any changes in the
direction of the fibers of the different hoop layers of the cylindrical composite pressure vessels
facilitated the damage of even more layers to concentrate stress in one point thus bring about
failure from the reduced burst pressure. As more compressive forces are applied on the hoop
layer of the vessel, the crack development was seen to move further from the impact point. The
ansys model was seen to significantly predict the finite element method results.
Bibliogaphy
Changliang, Z., Mingfa, R., Wei, Z. and Haoran, C. Delamination prediction of composite
filament wound vessel with metal liner under low velocity impact. Composite structures, Vol 75,
No. 1-4, 2016, pp.387-392.
Faggiani, A. and Falzon, B.G. Predicting low-velocity impact damage on a stiffened composite
panel. Composites Part A: Applied Science and Manufacturing, vol 41, No. 6, 2010, pp.737-749.
Ganapathy, S., and K. P. Rao. "Failure analysis of laminated composite cylindrical/spherical
shell panels subjected to low-velocity impact." Computers & structures 68, no. 6 2018: 627-641.
Gong, S. W., Shim, V. P. W., and Toh, S. L., “Impact Response of Laminated Shells with
Orthogonal Curvatures,” Composites Engineering, Vol. 5, No. 3, 2015, pp. 257–275.
Kim, E.H., Lee, I. and Hwang, T.K. Low-velocity impact and residual burst-pressure analysis of
cylindrical composite pressure vessels. Aiaa Journal, vol 50, No. 10, 2012, pp.2180-2193.

Matemilola, S. A., and Stronge, W. J., “Impact Response of Composite Cylinders,” International
Journal of Solids and Structures, Vol. 34, No. 21, 2011, pp. 2669–2284.