Livermore Software Technology Corporation | Date: 2015-09-15
Characteristics of a blast source and a FEA model representing a surrounding fluid domain are defined. One layer of new border nodes and elements are created outside of the fluid domains original outer boundary formed by the original border elements. Each new border element/node is associated with one of the original border elements/nodes as corresponding master element/node. At each time step of a time-marching simulation of an underwater explosion, simulated fluid behaviors are computed for all but the new border elements. The computed fluid behaviors of each original border element are saved into a corresponding lookup table configured to store the computed fluid behaviors for a predefined number of time steps in a first-in-first-out manner. Simulated fluid behaviors of each new border element are determined by interpolating, with the calculated blast wave propagation time from the master element, the stored fluid behaviors in the corresponding master elements lookup table.
Livermore Software Technology Corporation | Date: 2015-08-25
Meshfree model containing a number of particles to represent a structure made of brittle material is defined. At each non-initial solution cycle of a numerical simulation using the meshfree model based on damage mechanics, the following operations are performed: (a) determining one or more damage zones in the structure from simulated structural responses obtained in immediate prior solution cycle; (b) dividing the particles into a first group representing the damage zones and a second group representing the remaining of the meshfree model; (c) applying a meshfree regularization scheme by modifying each particles strain field of the first group with a morphing function that ensures a homogeneous jump condition along respective borders of the damage zones; and (e) obtaining simulated structural behaviors of the structure using a meshfree stabilization scheme that applies to all of the particles strain field. Each damage zone represents a crack that can grow over time.
Livermore Software Technology Corporation | Date: 2015-10-27
FEA model contains first and second layers of nodes to form a group of node-pairs, each containing one node in the first layer and a corresponding node in the second layer. Nodes in each node-pair are located in a substantially closer distance comparing with distances to other nodes. Candidate finite elements for controlling time-step size are identified. Each candidate finite element is defined by one or more node-pairs. At each solution cycle of a time-marching simulation, nodal forces of the FEA model including candidate finite elements are obtained. A scaled dimension is calculated by multiplying the smallest dimension with a speed-up scale factor. A critical dimension for controlling the next solution cycles time-step size is then determined. A fraction of the corresponding nodal forces to be redistributed for maintaining a stable solution are calculated and redistributed according to a formula based nodal masses and speed-up scale factor.
Livermore Software Technology Corporation | Date: 2015-05-17
Methods and systems for creating a computerized model representing a layered shell-like structure are disclosed. 2-D reference mesh model and a user-specified definition of a layered shell-like structure are received in a computer system. The 2-D reference mesh model contains a plurality of reference nodes connected by a plurality of 2-D reference elements for representing the layered shell-like structures mid-plane in the 2-D reference mesh models thickness direction and the user-specified definition includes the number of layers and each layers characteristics. A set of new nodal locations along respective reference nodes normal vectors are calculated according to a set of rules derived from the user-specified definition. New nodes for defining a computerized model that represents the layered shell-like structure are created by reproducing the reference nodes at each corresponding new nodal location. And corresponding finite elements of the computerized model at respective layers are formed according to the user-specified definition.
Livermore Software Technology Corporation | Date: 2015-05-06
Methods and systems for specifying metal necking failure criteria in FEA are disclosed. FEA model contains many finite elements representing a structure, a loading condition and a metal necking failure criteria are received in a computer system. The loading condition includes a loading direction. The metal necking failure criteria includes critical strain and fracture strain values, the necks width, and a profile of strain values between the critical strain value and the fracture strain value within the necks width. At each solution cycle in the time-marching simulation of the structure, each finite element is check to determine whether it experiences a metal necking failure, which occurs when each finite elements strain obtained in that solution cycle is greater than an average strain value defined in a formula according to the critical strain and fracture strain values, the necks width and the profile of the metal necking failure criteria.
Livermore Software Technology Corporation | Date: 2015-09-22
A FEA model, representing a structure, contains at least many finite elements for metal portion, a set of metal necking failure criteria (critical and fracture strain values defined in form of a loading path diagram) and the necks characteristics (necks width and a profile of strain values within the width) are received in a computer system. At each solution cycle of a time-marching simulation using the FEA model, following operations are performed at each integration point of every finite element: identifying major and minor strain values and corresponding directions from the computed strain values, calculating an equivalent metal necking failure strain value (_(e)) in the major strain direction with a formula based on corresponding critical and fracture strain values, the necks characteristics and a characteristic dimension with respect to the major strain direction, and determining metal necking failure, which occurs when the major strain value is greater than _(e).
Livermore Software Technology Corporation | Date: 2016-05-17
Systems and methods of deriving peak fracture strain values of a metal experiencing fracture failure from measured data obtained in a specimen test are disclosed. Metal fracture failure criteria, a measurement characteristic length in a specimen test and characteristics of a neck formed in the metal are received in a computer system. The metal fracture failure criteria contain respective measured critical strain value and average fracture strain value in various loading conditions. The characteristics of the neck include the necks width and a profile of strain distribution within the necks width. Respective peak fracture strain values are calculated for various loading conditions using a formula based on the profile of strain distribution, the necks width, and measured critical strain value and average fracture strain value. Peak fracture strain values can be used in a numerical simulation of sheet metal deformation for more accurately predicting structural behaviors of metal.
Livermore Software Technology Corporation | Date: 2015-04-22
FEA model representing a reinforced concrete structure is defined and received in a computer system. The FEA model contains a number of solid elements defined by a number of solid element nodes and a number of beam elements defined by a number of master beam element nodes. Beam elements representing reinforcing steel are embedded inside solid elements representing concrete. Each beam element straddles one or more solid elements. Slave beam nodes along the at least one beam element are created such that each of the solid elements houses at least one slave beam node. Numerically simulated structural behaviors of the reinforced concrete structure are obtained by conducting a time-marching simulation using the FEA model. At each of the many solution cycles of the time-marching simulation, proper coupling of the solid elements and the at least one beam element are ensured.
Livermore Software Technology Corporation | Date: 2015-01-15
FEA model representing a stamped sheet metal before trimming and a trimming operation setup are received. Each trim steel contains a set of cutting-edge nodes associated with a trim vector. At least one trim line is established by projecting cutting-edge nodes onto the FEA model according to the trim vector. Numerically-constrained node-pairs along the trim line are created at intersections with edges of crossed finite elements. The FEA model is modified by splitting crossed finite elements to preserve the original geometry and to ensure numerical stability. New finite elements are defined using one of the nodes in corresponding node-pairs such that no finite element straddles the trim line. At each solution cycle of a time-marching simulation of trimming operations, the numerical constraint is released for each node-pair determined to be reached by one of the cutting-edge nodes. Simulated structural behaviors are obtained as the scrap portion(s) deforms and falls accordingly.
Livermore Software Technology Corporation | Date: 2015-01-06
Numerical simulation of bi-phase material that changes phase after crossing a directional spatial boundary is disclosed. FEA model contains finite elements for representing bi-phase material. Each finite element is associated with a material identifier containing first and second sets of material properties for respective first and second phases of the bi-phase material. All finite elements are initially assigned with the first set of material properties. At each solution cycle during a time-marching simulation of the bi-phase material, the second set of material properties under the same material identifier is assigned to those of the finite elements determined to have moved across the direction spatial boundary for instant phase change. Material properties of a finite element located in the transition region are calculated by interpolating first and second set of material properties for gradual phase transition. Numerically-simulated structural behaviors are calculated with finite elements grouped together under the same material identifier.