Abstract: Methods and systems for enabling simulation of material aging effect of chrono-rheological materials in computer aided engineering (CAE) analysis are disclosed. According to one aspect, a set of material property tests is conducted for a chrono-rheological material of interest. Each test obtains a series of material properties such as relaxation test data at different age. The relaxation test data are measured by maintaining a specimen of the chrono-rheological material at a predetermined strain. A set of first and second time-dependent material aging effect parameters is determined by shifting and matching the series of relaxation test data between each pair of the tests.

Abstract: Improved topology optimization for engineering product design is disclosed. An engineering product including a design domain to be optimized is defined. Design domain can be a portion of or the entire engineering product. Design objective and optional constraint are also defined such that optimization goal can be achieved. Additionally, initial configuration of the design domain is represented by a finite element analysis (FEA) mesh. Each element or element group is associated with a design variable. A set of discrete material models is created from the baseline material used for the design domain. The set of discrete material models is configured to cover entire range of the design variable and each discrete material model represents a non-overlapping portion. Each element representing the design domain is associated with an appropriate discrete material model according to the design variable.

Abstract: Systems and methods of simulating an explosion in time-marching finite element analysis are disclosed in the present invention. According to one aspect, a method is configured for increasing user (e.g., engineer or scientist) productivity by reducing computation time of simulating fluid-structure interaction due to an explosion. The method comprises a creation of a finite element analysis model that includes structure, surrounding fluid, a blast source of the explosion and a single layer of ambient elements each having a segment representing a boundary of the fluid facing the blast source. Each ambient element is associated with a particular finite element representing the fluid at the boundary. The ambient elements are configured to be situated between the blast source and the structure such that the simulation can be carried on a set of boundary conditions specified thereon. The boundary conditions comprise a set of nodal velocities that are determined from the empirical formula (e.g.

Abstract: Simulation of thermal fluid-structure interaction using bulk flow fluid elements (BFFEs) is described. Each BFFE is configured to include the following characteristics: 1) at least one surrounding layer of solid elements representing either the surrounding structure or the pipe wall; 2) a layer of shell elements or Bulk Node Segments representing the outer boundary of the fluid; 3) a Bulk Node at the center of the BFFE for defining fluid properties (e.g., density, specific heat) and volume (i.e., fluid volume is calculated as the enclosed volume between the Bulk Node and all of the Bulk Node Segments that surround it); 4) a fluid flow beam element or Bulk Node Element for defining fluid flow path to another BFFE; and 5) a contact interface between the solid elements and the shell elements for conducting fluid-structure thermal interaction.

Abstract: A computer-implemented method of simulating an impact event in a finite element analysis used for assisting users to design or improve one or more structures is described. The structures are represented in a finite element analysis model that is divided or partitioned into a plurality of domains. Efficiency of the method is achieved when used in a computer system having multiple processing units and multiple contact interfaces defined and specified by users (engineers and/or scientists). Each domain is associated with or assigned to one of the processing units. A “group-able” correlation is established or determined between domains and contact interfaces so that data communications can be conducted in most efficient manner, for example, minimizing idle processing units during data communications.

Abstract: System and method of simulating large deformation and rotation of a structure in a finite element analysis used for improving structural design is disclosed. According to one aspect, a special purpose solid finite element is configured for simulating large deformations and/or rotations of a structure. The special purpose solid finite element comprises only corner nodes with each node having six degrees-of-freedom (DOF), three translational and three rotational. In other words, each node is configured to include translational deformation and rotation deformation, each of the translational and rotational deformation has three components corresponding to one of the six DOFs. According to another aspect, the special purpose solid element has a plurality of external edges. Each external edge has two ends, each end is located at one of the adjacent corner nodes.

Abstract: Each spot weld in a structure is represented by a cluster of at least one solid element in a finite element analysis model of the structure. Each spot weld is used for tying together two parts. Each of the two parts are generally represented or modeled as a number of two-dimension shell elements. Since the tie-connection between the spot weld and the two parts can be located arbitrarily within the respective part, the shell elements representing the two parts do not have to be aligned in space. The only requirement is the two shell elements must be overlapped each other such that the spot weld can tie the two shell elements (i.e., one from each part) together. A spot weld failure criterion used for determining failure including shear and axial stresses acted on the spot weld, shell element size and spot weld location sensitivity scale factors and strain rate effect.

Abstract: A system, method and software product for prescribing rigid body in finite element analysis is described. According to one aspect, user defines a rigid body orientation time history based on a variety of schemes including, but not limited to, direction cosine, orientation angles, Euler parameters, Rodriguez parameters, and Caley-Klein parameters. The unique combination in one of the schemes is converted to direction cosine time histories first. The direction cosine matrix can then be interpolated from either the defined or the converted direction cosine time history at each solution cycle. The time derivative of the direction cosine matrix and the resulting angular velocity matrix are calculated. The solution for the equation of motions is obtained using calculated angular velocity for each solution cycle until the simulation ends. According to another aspect, the present invention interpolates user specified rigid body orientations time history in several schemes including, piecewise linear, cubic spline.

Abstract: A method, system and computer program product pertained to adaptive discretization refinement of shell structure is disclosed. The adaptive mesh-free model is based on a technique for dividing the critical area into a finer model. The present invention is a method for enabling adaptive mesh-free shell structure in a time-domain analysis, the method comprises: defining the mesh-free shell structure by a structural geometry description file including a plurality of nodes and a reference 3-D mesh, which includes a plurality of shell elements, mapping the 3-D reference mesh into a 2-D parametric plane, wherein the 2-D parametric mesh includes a plurality of integration cells corresponding to the plurality of shell elements, solving structural responses at current solution cycle using mesh-free mathematical approximations pertaining to each of the plurality of integration cells, performing adaptive discretization refinement for the plurality of the integration cells.

Abstract: In one aspect of the invention, each bolt is modeled using a beam element in a FEA model. To apply desired pretension to one or more bolts, at least one pretension-versus-time curve is specified. Each pretension-versus-time curve includes ramp portion, desired pretension portion and optional unloading portion. Duration_of the pretension-versus-time curve generally covers first 0.5-1% of total simulation time of a car crashworthiness analysis. Ramp portion starts from zero to desired pretension in a substantially linear manner, and hence being configured for applying desired pretension to a bolt gradually with smaller increments. Desired pretension portion is configured for ensuring the desired pretension can actually be applied to the beam element during an initialization process—a series of quasi-static analyses. Since the method is independent of the deformation of the beam, the method completely avoids the need to iteratively determine an axial strain or displacement that gives the desired pretension.

Abstract: Shapeable materials of interest are modeled with a rectangular mesh having N columns and M rows of substantially similar shell elements. The shapeable materials of interest are held in tension between a sink and a source. A column of fictitious elements is added to make the mesh wrapped-around continuous. The fictitious elements are marked as inactive, while other elements are marked as active. As the simulation moves on, the active elements are marched in the product producing direction of the machinery. When a pre-defined distance has traveled in the simulation the present invention performs the following: Activate inactive elements at the source; Copy all history data including stresses from the last column of active elements to newly activated elements; Deactivate the lead column of active elements at the sink; and Move the set of nodal boundary conditions to newly established boundary nodes at the sink and the source.

Abstract: A two-level transformation scheme to enable a practical fast mesh-free method is disclosed. The first level transformation transforms the original chosen mesh-free shape function to a first transformed mesh-free shape function that preserves Kronecker delta properties. The first transformed mesh-free function allows the essential boundary conditions to be imposed directly. The second-level transformation scheme employs a low pass filter function served as a regularization process that filters out the higher-order terms in the monomial mesh-free approximation obtained from the first-level transformation scheme with desired consistency and completeness conditions. This integration scheme requires only a low-order integration rule comparing to the high order integration rule used in the traditional mesh-free methods. The present invention simplifies the boundary condition treatments and avoids the usage of high-order integration rule and therefore is more practical than the traditional mesh-free methods.

Abstract: System and method for enabling direct determination of rigid body motion using data collected from a plurality of independent accelerometers are disclosed. A mechanical object that can be theoretically emulated as a rigid body is instrumented with a plurality of accelerometers at different locations. Direct determination of rigid body motion at a location of interest includes following operations at each solution time step: transform local acceleration to global, integrate accelerations to obtain velocities, calculate direction cosine matrix using the angular velocity matrix, form a first set of redundant equations, obtain the angular velocity by solving the first set of equations using either least squares fitting or a selective Gaussian elimination scheme, form a second set of redundant equations and obtain the translational velocity by solving the second set of equations using either the averaged value or a pre-defined rule such as minimizing the contribution from the rotational term.

Abstract: Systems and methods of selecting a solver with appropriate numerical precision in each of a series of hierarchically related engineering simulations are described. According to an exemplary embodiment of the present invention, a series of hierarchically related engineering simulations comprises a sequence of finite element analyses for designing and analyzing a structural product. An input file describing the structural product and type of engineering simulation is received. Each different type of engineering simulations is checked to determine which solver with appropriate numerical precision (i.e., single or double precision) is used. A corresponding executable module (e.g., Finite Element Analysis software module) is then used for performing the analysis of that engineering simulation. The process repeats until all of the engineering simulations have been conducted in the entire sequence.

Abstract: A system, method and software product for modeling spot welds in a finite element analysis is described. The spots welds are represented by beam elements or solid elements in accordance with an indicator flag. The flag may also be specified as the number (e.g., an integer such as 1, 4, 8 or 16) of solid elements in a cluster representing spot weld. The solid elements may include, but not limited to, hexahedron, tetrahedron, and the likes. The number of solid elements and required nodes are generated for each spot weld based on the indicator flag. A table is formed to group the generated solid elements in a cluster together, so that the force and moment resultants of the spot weld can be computed and assembled in a file.

Abstract: A sampling strategy using genetic algorithms (GA) in engineering design optimization is disclosed. A product is to design and optimize with a set of design variables, objectives and constraints. A suitable number of design of experiments (DOE) samples is then identified such that each point represents a particular or unique combination of design variables. The sample selection strategy is based on genetic algorithms. Computer-aided engineering (CAE) analysis or analyses (e.g., finite element analysis, finite difference analysis, mesh-free analysis, etc.) is/are performed for each of the samples during the GA based sample selection procedure. A meta-model is created to approximate the CAE analysis results at all of the DOE samples. Once the meta-model is satisfactory (e.g., accuracy within a tolerance), an optimized “best” design can be found by using the meta-model as function evaluator for the optimization method. Finally, a CAE analysis is performed to verify the optimized “best” design.

Abstract: Systems and methods of limiting contact penetration in numerical simulation of non-linear structure response using implicit finite element analysis are described. According to one aspect, a finite element analysis (FEA) model of a structure is defined as a number of nodes and elements based on geometry and material properties of the structure. A time-marching analysis of the FEA model is then performed. The time-marching analysis results contain a number of solutions of non-linear structure response at respective time steps. Solution at each time step requires at least one iteration to compute. Non-linear structure response is determined in the following manner: 1) determining a search direction; 2) calculating a contact penetration parameter in the search direction; and 3) finding a minimum energy imbalance location along the search direction as a solution which is further restricted by the CPP such that contact penetration of the structure is substantially limited.

Abstract: A system, method and software product for defining material properties hierarchically in a finite element analysis of a structure is disclosed. As a material type is created, the type is checked whether it is a root material type. If so, all of the material properties are defined explicitly in the current definition. Otherwise, the parent material type is searched and located first until the traversing finds a root definition. All of the material properties of the parent material type(s) found are read in and stored as the base properties of the material to be created. The material properties explicitly defined in the current definition of the material will either overwrite or add to the base properties. The material properties definition resembles a hierarchical tree: each of the material properties type has a parent material except the root material type which is on the top of the tree.

Abstract: Systems and methods of consuming radial basis function (RBF) based meta-models are described. In one aspect, a product is to be designed and optimized with a set of design variables, objectives and constraints. A number of design of experimentals (DOE) points are identified. Each of the DOE points represents a particular or unique combination of design variables. Computer-aided engineering (CAE) analysis/analyses is/are then performed for each of the DOE points. A RBF based meta-model is created to approximate the CAE analysis results at all of the DOE points. A crowding distance is calculated for each DOE point. The DOE points are sorted accordingly in a predetermined criterion such as descending order, from which a predefined number of the DOE points are chosen as RBF neuron centers. RBF parameters such as function type, width and weight factor are adjusted so that the meta-model can substantially match the CAE analysis results.

Abstract: A system, method and software product for simulating inflation of an enclosed volume using gas particles is described. A gas flow characteristics is defined. A group of gas particles is created in the enclosed volume to simulate the injected gas. The average velocity of the gas particles is determined by the temperature and the molar mass of the gas represented by the particles. The gas particles travel through the nozzle into the enclosed volume in random directions. All gas particles are checked for collisions with the boundary and with one another. After detection of a collision, the energy of the particle is transferred either to the boundary or anther particle. The kinetic energy of a gas particle includes a translation and a spinning-plus-vibration component. Only the translation component is transferred to the boundary, while both components are readjusted after a collision between two particles. In addition, the initial balance ratio is restored after a particle-to-particle collision.