> > Glossary for Creo Simulate

Glossary for Creo Simulate
Letters in parentheses indicate that the definition applies only to those Creo Simulate products. The possible letters are S (Structure) or T (Thermal). Otherwise, the definition applies to all Creo Simulate products.
 Term Definition 2D axisymmetric model See axisymmetric model. 2D plate element A three- or four-sided element that represents a plate in a 2D plane stress model. 2D plane stress model A two-dimensional model you can use when modeling a thin, flat plate. All elements must lie in the WCS Z=0 plane. You can only create 2D plate elements for a 2D plate model. 2D plane strain model A two-dimensional model representing a cross section of a structure that is very long in the dimension perpendicular to the cross section. In plane strain models, all out-of-plane components of load and strain must be zero, and loading cannot vary in the out-of-plane direction. For example, in Structure, you can use a plane strain model type for applications such as long pipes, dams, and retaining walls. In Thermal, you use 2D plane strain models for structures where the heat flow in one direction is negligible that is, the temperature varies in two directions but not the third. For example, you could use this model type for modeling a long pipe. 2D shell element A one-dimensional entity that represents a shell element in a 2D plane strain or 2D axisymmetric model. 2D solid element A three- or four-sided element that represents a 2D plane strain or 2D axisymmetric model. abscissa The horizontal axis of a graph. analysis An examination of your model through which Creo Simulate determines how the model behaves under specified conditions. You run an analysis as part of a standard or other design study. Structure calculates your model's response to a set of loads and constraints. See also these analysis types: buckling, contact, dynamic frequency response, dynamic random response, dynamic shock response, dynamic time response, modal, prestress modal, prestress static, and static. Thermal calculates your model's response to a set of heat loads that are subject to specified prescribed temperatures and/or convection conditions. See also steady-state thermal. animation A dynamic display of mode shapes, static displacement results, a variety of fringed results, and shape changes for a sensitivity or optimization study in both products. applied flux (T) A prescribed rate at which heat energy is applied. associativity How any entity (such as geometry, load, boundary condition) in Creo Simulate relates to any other entity. If one entity is related to a second entity, the definition of the first entity depends on the definition of the second. For instance, if a load is associated with a point and that point moves, the load also moves. AutoGEM (Automatic Geometric Element Modeling) Creo Simulate's automated process for generating geometric elements on a model. AutoGEM generates elements that comply with all element creation rules and that provide accurate results when Creo Simulate analyzes your model. axisymmetric model A two-dimensional model for which the geometry, loads, deformations, prescribed temperatures, and convection conditions are symmetric about an axis of rotation. For example, you can use an axisymmetric model type for a cylindrical or spherical structure, such as a storage tank. beam See beam element. beam element A one-dimensional entity used to represent part or all of a structural component that has a length much greater than its other two dimensions. The beam element axis lies on a curve or edge. In Structure, you describe the cross section by a set of section properties and an orientation. See also CY, CZ, IYY, IZZ, J, orientation, shear FY and FZ, and theta. bearing load (S) A load that approximates the pressure applied to a 3D surface or 2D circle by a rigid pin or axle passing through a hole. boundary condition (T) See convection condition and prescribed temperature. boundary condition set (T) A grouping of convection conditions and/or prescribed temperatures placed on a single model. You typically include a boundary condition set as part of an analysis. boundary edge An edge associated with only one shell or solid, unless the edge is associated with a solid and a shell coincident with a face of that solid. See also boundary face. boundary face A face that belongs to only one solid element. See also boundary edge. buckling analysis (S) An analysis that calculates the critical magnitudes of load at which a structure will buckle, and the model's stresses, strains, and deformations in response to loads and constraints that do not vary in time. buckling load factor (S) A quantity obtained by running a buckling analysis in Structure. The buckling load factor multiplied by the applied load yields the buckling load. bulk temperature (T) In convective heat transfer through a surface, the temperature of the fluid far from the surface. C1 continuous curve or surface A mathematical description of a curve or surface. A curve or surface is C1 continuous if both the direction and the magnitude of its first derivatives vary continuously everywhere on the curve or surface. C2 continuous curve or surface A mathematical description of a curve or surface. A curve or surface is C2 continuous if both the direction and the magnitude of its second derivatives vary continuously everywhere on the curve or surface. centrifugal load (S) An inertial body load that results from rotation about an axis, directed radially out from the axis. check button A square button on a dialog box. From a group of check buttons, you can select one or more. com_x, com_y, com_z (S) The location of the center of mass in relation to the WCS origin. conductivity (T) The physical property of a material that, for a given temperature gradient, governs the rate at which heat energy is transferred within the material. constraint (S) An external limit on the movement of a structure or part of a structure. You can constrain your model in any of the six degrees of freedom translation or rotation about any of the three coordinate directions. constraint set (S) A grouping of constraints placed on a single model. You typically include a constraint set as part of an analysis. contact analysis (S) A nonlinear analysis in which Structure calculates the contact area at each contact in a model, and the model's stresses, strains, and deformations in response to loads and constraints that do not vary in time. contour plot A type of result display that superimposes a set of curves on the model. Each curve has a color that represents a constant value of a specified scalar quantity. You also have the option of labeling contour plots for black-and-white printing. Examples of scalar quantities include stress, displacement, temperature, or flux components. convection condition (T) A boundary condition you can specify on the convective heat exchange between a moving fluid and geometric and/or element entities within your model. convergence The method Creo Simulate uses to find a solution to an analysis, based on your requirements and restrictions. There are two main convergence methods in Creo Simulate :multi-pass adaptive and single-pass adaptive. coordinate system A generic term for a system of coordinates enabling you to define precise locations of entities. Creo Simulate uses a default world coordinate system. In addition, you can create three types of user coordinate systems Cartesian, cylindrical, and spherical. You can specify orientation of a beam or spring by defining its local coordinate system. See also local coordinate system user coordinate system, view coordinate system, and world coordinate system. critical damping (S) Amount of damping below which oscillation occurs. See also damping coefficient. current body The body that is active and available for modification. You are always using the current body. current directory The directory from which you started Creo Simulate. current model The model you currently have open on the screen. Creo Simulate allows you to open only one model at a time. See also model. CY (S) The distance off a beam's neutral axis in the local Y direction at which you direct Structure to report bending stresses. cyclic symmetry A type of constraint that you create by making cuts in a model at two symmetric surfaces. Subsequent analyses can be done on the symmetric surfaces only, which can significantly reduce the analysis time. cyclic strain hardening exponent (n´) cyclic strength coefficient (K´) These properties are used to define the cyclic stress-strain curve for the material. ∆ɛ/2 = Δσ/2E+(Δσ/2K´)1/n´ Where, ∆ɛ/2 is the cyclic strain amplitude Δσ/2 is the cyclic stress amplitude E is the elastic modulus CZ (S) The distance off a beam's neutral axis in the local Z direction at which you direct Structure to report bending stresses. damping coefficient (S) The percentage of critical damping of a mode in a dynamic frequency response, random response, or time response analysis. A damping coefficient of 100% means the model is critically damped and does not vibrate freely. A damping coefficient of 1% means the amplitude decays by about 6% over a period of oscillation. See also critical damping. degrees of freedom A means of expressing the potential motion of a mechanical system. design study An examination of your model using one or more analyses you previously defined (standard study). A design study may also use an analysis to examine alternatives to your design (optimization and sensitivity studies). See also global sensitivity study, local sensitivity study optimization study, , and standard study. dialog box A separate window, invoked by a command, in which you enter values and other information. displacement (S) The movement of a point on the model, measured as the change in position relative to the point's location on the undeformed model. Displacements are calculated by default during an engine run. dynamic frequency response analysis (S) An analysis that calculates the amplitude and phase of displacements, velocities, accelerations, and stresses in your model in response to a load oscillating at different frequencies. dynamic random response analysis (S) An analysis that calculates the power spectral densities and RMS values of displacements, velocities, accelerations, and stresses in your model in response to a load of specified power spectral density. dynamic shock response analysis (S) An analysis that calculates maximum values of displacements and stresses in your model in response to a base excitation with a specified response spectrum. dynamic time response analysis (S) An analysis that calculates displacements, velocities, accelerations, and stresses in your model at different times in response to a time-varying load. element An entity based on your model's geometry that is used to analyze your model. Types of elements include beams, shells, solids, 2D shells, 2D solids, and 2D plates. Structure also has mass and spring elements. You create elements by using AutoGEM, Creo Simulate's automatic element generation technology. AutoGEM creates elements for your model at the start of every analysis. You can also manually start AutoGEM during your modeling session to evaluate and refine your mesh. See also AutoGEM or geometric element modeling. Encapsulated PostScript A PostScript file you can include in another PostScript file. Encapsulated PostScript files are used to place illustrations in a PostScript document. You cannot print out an Encapsulated PostScript file on its own. See also PostScript file. energy norm (T) A scalar quantity that is proportional to the integral over the element of the squared flux. It is analogous to element strain energy in a static structural analysis. You can create measures for this and use it for a convergence quantity. enforced displacement (S) A known displacement you prescribe on part of your model when you create a constraint. entity A general term for anything in a model, including points, curves, springs, beams, and so forth. There are also entities specific to each product for example, loads and constraints in Structure and convection conditions and heat loads in Thermal. entry box A box on a dialog box in which you enter data. You make an entry box active by moving your mouse cursor over the box and pressing the left mouse button. excluded element (S, T) An element you designate that is excluded from convergence and measure calculations because it is near a region of infinite or very high stress or flux that is not of primary concern. extensional stiffness (S) A spring stiffness constant that equals the ratio of spring force to displacement along a principal coordinate axis. fatigue strength coefficient (σf´ fatigue strength exponent (b) fatigue ductility coefficient (ɛf´) fatigue ductility exponent (c) These properties are used to define the total strain-life curve for the material. Δɛ/2 = (σf´/E) (2N)b+ɛf´(2N)c Where, N is the number of reversals to failure E is the elastic modulus film coefficient (T) In convective heat transfer through a surface, the constant of proportionality between the flux through the surface and the difference between the surface temperature and the bulk temperature. flux (T) The rate at which heat energy is transferred per unit area. frequency response analysis (S) See dynamic frequency response analysis. fringe plot A type of result display that superimposes a set of colored regions on the model. Each color represents a different range of values of a specified scalar quantity, such as stress, displacement, temperature, or flux. G1 continuous curve or surface A mathematical description of a curve or surface. A curve or surface is G1 continuous if the direction, but not necessarily the magnitude, of its first derivatives varies smoothly everywhere on the curve or surface. G2 continuous curve or surface A mathematical description of a curve or surface. A curve or surface is G2 continuous if the direction, but not necessarily the magnitude, of its second derivatives varies smoothly everywhere on the curve or surface. GEA See geometric element analysis. GEM See geometric element modeling. GEO See geometric element optimization. geometric element analysis (GEA) The technology for analyzing a model by analyzing its geometric elements to the polynomial order required to achieve the level of accuracy you specify. geometric element modeling (GEM) The technique for defining a model for analysis by breaking it up into elements that you associate directly with the geometry. See also element. geometric element optimization (GEO) A process that helps you determine the best balance between design constraints and performance by automatically varying the parameters that are associated with a geometric element model. See also optimization. global sensitivity study A design study in which Creo Simulate calculates the changes in your model's measures when you vary a parameter over a specified range. This is done by calculating measure values at regular intervals in a parameter's range. You can vary more than one parameter simultaneously. See local sensitivity study, optimization study, and standard study. gravity load (S) A body load that represents the effect of a uniform gravitational field or the inertial load of constant acceleration. heat capacity (T) A property that indicates the ability of a material to absorb heat from the external surroundings. It represents the amount of energy required to produce a unit temperature rise. heat load (T) A thermal load you can place on specific locations on your model to study the effects of internal heat generation or applied flux. If you specify a positive heat load, the load is adding heat to the model, making the load a heat source. If you specify a negative heat load, the load is removing heat from the model, making the load a heat sink. You can group heat loads into load sets. See also heat sink and heat source. heat sink (T) A prescribed rate of heat energy lost. See also heat load. heat source (T) A prescribed rate of heat energy generated. See also heat load. HPGL Hewlett-Packard Graphics Language, a page description format you can use to print on a plotter or printer that supports HPGL. inertia (Iy, Iz) (S) Factors that you specify for the second moment of area for a beam element. Along with Young's modulus, these properties describe stiffness in bending about a beam's principal Y and Z axes. isotropic Describes a material with an infinite number of planes of material symmetry, making the properties equal in all directions. You enter a single value for each property. You can assign isotropic materials to any element type. IYY (S) A beam cross section's second moment of area describing stiffness in bending about the local Y axis. IZZ (S) A beam cross section's second moment of area describing stiffness in bending about the local Z axis. J (S) A beam cross section's effective second polar moment of area describing stiffness in torsion. For circular cross sections, the effective second polar moment of area is equal to the actual second polar moment of area. Large Deformation Analysis An option you can select to compute large deformation results for static structural analyses only, using nonlinear equations. This is only available for 3D, 2D plane strain, and 2D plane stress model types. limit A value or range of values for a specified measure that Creo Simulate must respect during an optimization study. list box A list of items on a dialog box with a scroll bar to its right. load (S) A force you place on your model. You can specify the direction and magnitude of the force. See also bearing load, centrifugal load, gravity load, pressure load, and temperature load load set A grouping of structural loads or heat loads placed on a single model. You can include load sets in most analysis types. Creo Simulate calculates results separately for each load set, unless you use the Sum Sets option for a dynamic analysis. local coordinate system (M) The coordinate system specific to the body. You enter body points for a body relative to its local coordinate system (LCS). The default axis orientations are the same as those for the current coordinate system, either the WCS or a UCS. See also coordinate system, user coordinate system, view coordinate system, and world coordinate system. local sensitivity study A design study in which Creo Simulate calculates the sensitivity of your model's measures to slight changes in one or more parameters. The slope of the sensitivity curve between two sample points is calculated. See also global sensitivity study, optimization study, and standard study. mass element (S) An element that represents a concentrated mass and concentrated moment of inertia at a particular point of a model. mass properties Properties calculated from a model's geometry and material properties. The mass properties for the full model are included in the summary file when you run a design study with certain types of analyses. material damping A material property that allows you to model the dissipation of energy, caused by friction, heat exchange, or deformation, that occurs during a contact event. material orientation The principal material directions, relative to the current coordinate system, associated with the surfaces, volumes, shells, solids, 2D solids, or 2D plates in your model. You can specify both the coordinate system axis with which each principal material direction is aligned and an angle of rotation for those directions. See also orientation. material properties Properties of the material you assign to geometry or elements. The following list indicates the material properties for each product: • Coefficient of Thermal Expansion-S • Conductivity-T • Cost per Unit Mass-S, T • Mass Density-S, T • Poisson's Ratio-S • Shear Modulus-S • Young's Modulus-S See also isotropic, orthotropic, and transversely isotropic. material set A set of material properties. Material sets can reside in a material library and can be assigned to one or more entities in your model. maximum magnitude principal stress (S) The principal stress value having the maximum magnitude. For example, if the maximum principal stress is 100 but the minimum principal stress is 200, the principal stress with the greatest magnitude is the minimum principal stress (200). maximum principal stress (S) The most positive principal stress in the model. maximum shear stress The maximum shear stress (also known as Tresca stress), is defined as one half of the largest difference in the principal stresses at a given point. MCAD Mechanical computer-aided design, a type of software you can use to draw a mechanical model design. Creo Parametric is an example of an MCAD program. measure A scalar quantity of interest that Creo Simulate calculates in a design study. You can set up measures to monitor specific aspects of your model's performance. For instance, you might want to know the stress tangent to a fillet for the later calculation of fatigue. You can use measures as convergence criteria for an analysis or for an optimization study goal or limit. You also use measures to measure sensitivity to parameter changes in a local or global sensitivity design study. During a design study, Creo Simulate calculates results for the measures that are valid for each analysis in the study. For example, a stress measure is calculated for a static analysis but not for a modal analysis. Creo Simulate A family of design analysis products that enable you to simulate and optimize the structural and thermal performance of your designs before you build prototypes. The two main products are as follows: • Structure a structural design analysis tool • Thermal a thermal design analysis tool These two products are integrated, so that you can access either product from inside a single user interface. Your installation may also include the optional Vibration module, a vibration analysis tool integrated with Structure. menu A list of commands you can execute. menu item A command or submenu listed on a menu. message box A box displayed, that contains a message or a question. minimum principal stress (S) The least positive principal stress in the model. modal analysis (S) An analysis in which Structure calculates the natural frequencies and mode shapes of your model. mode tracking (S) During an optimization that includes a modal analysis, you can direct the Structure engine to follow a particular mode through the optimization, even if that mode's frequency becomes greater than or less than a neighboring mode's frequency. model Your representation on the computer of a structure or object. You can associate analyses and design studies with a model. modeling The process of simplifying and abstracting a structure, object, or physical system so that it can be represented mathematically and studied with the aid of a computer. Model Tree window A window that graphically shows features of a model, including simulation features (datum points, coordinate systems, datum curves, surface regions, and volume regions). model type The dimensional treatment you want Creo Simulate to apply for your model. The available model types are 3D, 2D plane strain, 2D plane stress, or 2D axisymmetric. modified Mohr theory A theory used for predicting the failure of brittle materials. It is a variant of the Coulomb-Mohr theory modified to better predict fracture in brittle materials. moment of inertia (S) An inertial constant that equals the ratio of applied moment to the resulting angular acceleration about an axis. multi-pass adaptive convergence The point during a run at which the results for the last calculation for an analysis differ from the results for the preceding calculation by less than a specified percentage. The quantities Creo Simulate uses to make this comparison depend on the convergence option you select when defining the analysis. Creo Simulate increases the polynomial order along each edge of the model until either convergence or the maximum polynomial order has been reached. See also polynomial order. net heat flux (T) A measure that Thermal calculates by finding the total amount of heat that flows through one or more of the boundaries of one or more elements. For example, in 3D models, Thermal can calculate the net heat flux for the endpoints of beams, the edges of shells, the faces of solids, or a combination of these. optimization study A design study in which Creo Simulate adjusts one or more parameters to best achieve a specified goal or to test feasibility of a design while respecting specified limits. See also global sensitivity study, local sensitivity study, and standard study. Ordinate The vertical axis of a graph. orientation (S) A property of beams and two-point springs. Orientation is a vector with three WCS components. This vector specifies the beam's or spring's local Z axis relative to the WCS. See also material orientation. orthotropic Describes a material with symmetry relative to three mutually perpendicular planes. You can assign orthotropic properties to surfaces and parts. parameter space The representative space, internal to Creo Simulate's code, in which Creo Simulate represents geometric entities. Creo Simulate simultaneously represents all geometry by two methods the actual 2D or 3D representation of your model, and the 1D, 2D, or 3D parametric representation that Creo Simulate uses to manipulate geometric entities. Creo Simulate performs many operations on geometric entities in parameter space and then maps the entities back to 3D space. As a result, the appearance of an entity may differ significantly from its parametric representation. phase (S) The angle by which an output quantity is out of phase with the force that prompted the response. A negative angle means that the output quantity lags behind the force. p-level The highest polynomial order to which Creo Simulate performs calculations on a given edge during a run of a design study. See also polynomial order. plotting grid The locations at which Creo Simulate calculates values for displacement, stress, temperature, flux, and other quantities. Creo Simulate places a grid across each element and calculates a value at each location where two grid lines cross, or where a grid line intersects an element edge. You can determine the size of the grid when you define an analysis by specifying how many intervals along each element edge Creo Simulate uses to create the grid. The grid size affects the level of detail of the results. Poisson's ratio (S) The ratio of lateral contraction to longitudinal extension when a material is under tension. You specify Poisson's ratio when you define material properties. polynomial order When Creo Simulate runs a design study, it calculates the value of specified quantities at successively higher polynomial orders for each edge until it reaches convergence or the maximum polynomial order. Creo Simulate uses functions that may range from linear to a 9th order polynomial, although you can specify a subset of that range when you define an analysis. See also convergence and p-level. PostScript file A file written in the PostScript language, a page description language. You can create color or black-and-white files in PostScript format from Creo Simulate to print out on PostScript printers. p-pass A single analysis calculation by the Structure engine with each element edge set to a particular polynomial order. After each p-pass, Creo Simulate updates the polynomial orders of the edges for the next p-pass. The process continues until either convergence or the maximum polynomial order is reached. prescribed temperature (T) A temperature boundary condition that you specify for a geometric or model entity. Thermal determines the temperature at every location on your model for which you have not prescribed a temperature. You can add prescribed temperatures to new or existing constraint sets. pressure load (S) A load that acts normal to a surface and has units of force per unit area. prestress modal analysis (S) An analysis that calculates natural frequencies and modes of a prestressed model. The stress stiffness is calculated using stresses from a previous static analysis, then added to the elastic stiffness to create a combined stiffness. The combined stiffness is then used in place of the elastic stiffness for the modal analysis. prestress static analysis (S) An analysis that calculates deformations, stresses, and strains of a prestressed model. The stress stiffness is calculated using stresses from a previous static analysis, then added to the elastic stiffness to create a combined stiffness. The combined stiffness is then used in place of the elastic stiffness for the static analysis. prompt A request for a single input that appears on the command line. properties See CY, CZ, IYY, IZZ, J, mass properties, material properties, orientation,shear FY and FZ, shell properties, theta. push button A button on a dialog box that enables you to select an action that Creo Simulate performs. Typical push buttons include OK or Cancel. Q (T) The heat rate you apply to selected entities when you create a heat load. radio button A diamond-shaped or circular button on a dialog box. From a group of radio buttons, you can select only one. random response analysis (S) See dynamic random response analysis. reaction forces (S) The forces present at constrained edges or points. See also resultant. resultant (S) You can define a resultant force or resultant moment measure. Structure calculates the resultant force measure by integrating the total traction forces acting on one or more of the boundaries of one or more elements. Structure calculates the resultant moment measure by integrating the product of a moment arm and the traction forces acting on one or more of the boundaries of one or more elements. In 3D models, Structure can calculate a resultant measure for the endpoints of beams, the edges of shells, the faces of solids, or a combination of these. The value of a resultant measure is equal to the sum of the resultants for all of the entities selected. result window A single display of a design study result. A result window contains one quantity, such as stress or displacement, defined over a location, such as an edge or the entire model, in a specific graphic display, such as a graph or fringe plot. right-hand rule A method for determining the direction of the positive Z axis relative to the positive X and positive Y axes. If your right hand is in front of you with the palm up, your thumb pointing to the right represents the positive X axis, and your index finger pointing straight ahead represents the positive Y axis. If you then bend your middle finger up by 90 , it represents the direction of the positive Z axis. rigid body modes (S) Modes that have no strain associated with them. rotation (S) The local change in orientation at a location on the model relative to the undeformed model. run During a run, the engine performs the calculations needed to provide results for a specified design study. sensitivity study A "what if" design study where Creo Simulate uses parameters to study variations in the design of your model to help you find the best design. See also global sensitivity study and local sensitivity study. shape history An animation sequence showing the changing shape of your model during each step of an optimization or global sensitivity design study. You also use a shape history result window definition to save the optimized version of a model. shear FY and FZ (S) The ratio of a beam's effective "shear area" to its true cross-sectional area for shear in the Y direction (for shear FY) or in the Z direction (for shear FZ). Structure uses these factors to improve the accuracy of calculations involving beams. shell element A three- or four-sided entity used to represent part or all of a structural component that has a thickness much smaller than its other two dimensions. Creo Simulate displays the shell element midsurface. shell properties The properties you assign to a shell depend on its type. For a homogeneous shell, which consists of a single material whose properties do not vary through the shell's thickness, you assign a thickness. For a laminated shell, which consists of one or more materials whose properties may vary through the shell's thickness, you specify laminate stiffness properties. shock response analysis (S) See dynamic shock response analysis. simulation features Features that you can create in the Creo Simulate environment that allow you to focus on a portion of your model that the feature will simulate. Simulation features are only visible in the Creo Simulate environment, and include datum points, coordinate systems, datum curves, surface regions, and volume regions. single-pass adaptive convergence A method Creo Simulate uses to find a solution to your analysis. Creo Simulate runs a first pass with the polynomial order set to 3, estimates stress errors, raises the polynomial order of each element to a higher level based on the magnitude of the local stress errors, and then carries out a second solution using the updated polynomial orders. The results of this second solution are output as the final results. singularity A region of the model where the results are theoretically infinite for any physical quantity, such as displacement, stress, temperature, or heat flux. Singularities usually result from point loads, point constraints, and reentrant corners. solid element A cubical, tetrahedral, or wedge-shaped entity you use in Creo Simulate to represent a part or all of a three-dimensional structural component. spatial variation The process by which Creo Simulate spatially varies a Structure load or a Thermal heat load. You can direct Creo Simulate to vary a load or heat load linearly, quadratically, or cubically along an edge, curve, face, or surface. specific heat (T) The heat capacity per unit mass. See heat capacity. spline A continuous curve that is typically composed of several polynomial segments. spring (S) An idealization that represents an elastic spring connection between two points or an elastic spring connection to ground at a single point. standard study A study in which Creo Simulate calculates results for one or more analyses. You can specify different parameter settings for the analysis. See design study,global sensitivity study, local sensitivity study, and optimization study. static analysis (S) An analysis in which Structure calculates a model's stresses, strains, and deformations in response to loads that do not vary in time, where the model is also subject to constraints. steady-state thermal analysis (T) An analysis in which Thermal calculates your model's response to a set of specified heat loads, subject to any convection conditions and/or prescribed temperatures. This is the only type of analysis available in Thermal. temperature load (S) A body load due to a temperature change over the model. A temperature change causes local expansion or contraction of the model. You can cause the model to resist expansion or contraction by using constraints. The two types of temperature load are MEC/T and global. tensile/compressive/shear failure stress The maximum stress a body can endure under a tensile/compressive/shear load before failure occurs. thermal expansion coefficient (S) A material constant that equals the ratio of strain to temperature change in degrees. theta ( ) (S) A property of beams and two-point springs. Theta is the angle between the principal Z axis and the local Z axis. The default local Y axis lies in the plane of the beam unless theta is nonzero. time response analysis (S) See dynamic time response analysis. torsional stiffness (S) A spring stiffness constant that equals the ratio of spring moment to rotation about a principal coordinate axis. transient thermal analysis (T) An analysis in which Thermal calculates temperatures and heat fluxes in your model at different times in response to specified heat loads and subject to specified prescribed temperatures and/or convection conditions. transversely isotropic Describes a material with rotational symmetry about an axis that you can assign to surfaces and parts. The properties are equal for all directions in one plane, the plane of isotropy. You enter two values for each property, one for the plane of isotropy, and one for the remaining principal material direction. true angle The actual, absolute 3-D angle (as opposed to a projected angle). Tsai-Wu failure criterion A general multiaxial failure theory used to predict failure of anisotropic materials. It is named after Stephen Tsai and Edward Wu, who proposed the theory. Tsai-Wu normalized interaction term A mathematical term used in the calculation of the Tsai-Wu failure criterion. It represents the interaction between the normal stresses in material directions 1 and 2. See also material orientation and transversely isotropic. UCS See user coordinate system. user coordinate system A Cartesian, cylindrical, or spherical coordinate system you define, which is also referred to as a UCS. See also coordinate system, local coordinate system, view coordinate system, and world coordinate system. VCS See view coordinate system. Vibration An optional vibration analysis module integrated with Structure. view coordinate system The system Creo Simulate uses to define the view window. The origin is always at the center of your screen with the positive X axis horizontal and to the right, the positive Y axis vertical and up, and the positive Z axis perpendicular to the other axes and pointed at you as you sit at the computer. See also coordinate system, local coordinate system, user coordinate system, and world coordinate system. This coordinate system is a reference point for view changes. When you rotate, translate, or zoom your model, you are in effect repositioning the VCS in relation to your model. volume A set of associated surfaces that visually represents an entity with volume. A volume must be closed, but can have interior voids. von Mises stress (S) An equivalent stress that is a combination of all stress components. The von Mises yielding criterion states that a material reaches its elastic limit if the von Mises stress is equal to the material's yield stress in simple tension. WCS See world coordinate system. work area The largest window of the Creo Simulate screen, where you create and modify models, and review results. By default, the work area is below the command area and tools button area and to the left of the design menu area. world coordinate system The default coordinate system, also referred to as the WCS, in Creo Simulate. You use this coordinate system when you create your model. See also coordinate system, local coordinate system, user coordinate system, , and view coordinate system. Young's modulus (S) The ratio of stress to strain for a specific material, describing its stiffness. You specify Young's modulus when you define material properties. yield stress The value of stress at or above which a material no longer exhibits linear elastic behavior.