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Finite element analysis (FEA) of a composite overwrapped pressure vessel (COPV) has traditionally been a tedious and time consuming task. FEA is often omitted in the development of many vessels in favor of a “build and burst” philosophy based only on preliminary design with netting analysis. This is particularly true for small vessels or vessels that are not weight critical. The primary difficulty in FEA of a COPV is the creation of the model geometry on the sub-ply level.

Turon’s methodology for determining optimal analysis parameters for the simulation of progressive delamination is reviewed. Recommended procedures for determining analysis parameters for efficient delamination growth predictions using the Abaqus/Standard cohesive element and relatively coarse meshes are provided for single and mixed-mode loading.

Structures in general are subject to uncertainty due to manufacturing, assembly, environment of work, loads, etc … This scatter more specifically is associated for example to tolerances of thickness, position, waviness, etc, material mechanical properties distribution, layup alignment axes. All these deviations can be taken into account with stochastic analysis to reduce the total cost of the project considering all the phases of product life (manufacturing, assembly, maintainability…) and make a global robust design.

Thermal Barrier Coatings (TBC) have been used for almost three decades for heat insulation in high-temperature components to increase efficiency. Reliable diagnostic techniques that are practical to implement are needed to identify the location and severity of degradation in TBCs to protect against premature TBC failure. Luminescence spectroscopy has been utilized in detecting early damage, as it exhibits monotonic changes in the spectral characteristics with damage. Nevertheless there is still no agreement on what are the best spectral parameters that indicate damage.

Bird impact damage in complex aircraft structure has been investigated using explicit transient dynamic analysis by Abaqus/Explicit in order to fully employ its large library of elements, material models and the ability of implementing user defined materials. The numerical procedure has been applied on the very detailed large airplane secondary structure consisting of sandwich, composite and metallic structural items that have been modeled with 3D, shell and continuum shell elements, coupled with appropriate kinematic constraints.

Innovative composite structures are increasingly being used in the aircraft industry. A critical point of these new composite parts is the attachment to the surrounding aircraft structure. In cooperation between different EADS Business Units, a new advanced composite load introduction rib is developed to minimize weight and manufacturing costs. The new design of the flap focuses on the load introduction rib and drive fitting including the integrated lugs for the attachment to the flap support structure.

Boeing and Skyhook International entered into an agreement whereby Boeing will design and build two prototypes of the new Skyhook HLV aircraft. This hybrid airship is intended to carry 40 tons of cargo 100 miles. Due to the flexible, non-linear nature of fabric airship envelopes, as well as the complexity of designing a hybrid airship, the internal loads model for this aircraft is being developed in Abaqus and will be solved non-linearly.

Hello everybody,



I want to simulate a tensile test using "damage for ductile metals" and "ductile damage". ABAQUS requires three parameters:

-Equivalent fracture strain at damage initiation (a)

-stress-triaxiality (b)

-strain rate (c)

I have already seen Abaqus analysis user's manual (23.2.2), but there's no example. 



Currently, I defined a 3D solid deformable  and an elastic and plastic behavior. I do not understand how to select a first set of parameters for the "ductile damage".

** MATERIALS

Hi,

I'm conducting hypoplastic VUMAT model in abaqus. It always has the following problem. 

***ERROR: Bad Material definition in element number 1: zero or negative
initial dilatational modulus caused by bad material data. Please
check your material input and any initial conditions if necessary.

For the single layer,it works well,but this problem will appear for two layers, even if I chose the same parameters.

Hoping anyone who has the same problem or has already settled successfully could give me some advice.