ProductsAbaqus/StandardAbaqus/CAE Linear magnetic behaviorLinear magnetic behavior is defined by direct specification of magnetic permeability. Directional dependence of magnetic permeabilityIsotropic, orthotropic, or fully anisotropic magnetic permeability can be defined. For non-isotropic magnetic permeability a local orientation for the material directions must be specified (Orientations). Isotropic magnetic permeabilityFor isotropic magnetic permeability only one value of magnetic permeability is needed at each temperature and field variable value. Isotropic magnetic permeability is the default. Input File Usage MAGNETIC PERMEABILITY, TYPE=ISOTROPIC Abaqus/CAE Usage Property module: material editor: Type: Isotropic: Orthotropic magnetic permeabilityFor orthotropic magnetic permeability three values of magnetic permeability (, , ) are needed at each temperature and field variable value. Input File Usage MAGNETIC PERMEABILITY, TYPE=ORTHOTROPIC Abaqus/CAE Usage Property module: material editor: Type: Orthotropic: Anisotropic magnetic permeabilityFor fully anisotropic magnetic permeability six values (, , , , , ) are needed at each temperature and field variable value. Input File Usage MAGNETIC PERMEABILITY, TYPE=ANISOTROPIC Abaqus/CAE Usage Property module: material editor: Type: Anisotropic: Frequency-dependent magnetic permeabilityMagnetic permeability can be defined as a function of frequency in a time-harmonic eddy current analysis. Input File Usage MAGNETIC PERMEABILITY, FREQUENCY Abaqus/CAE Usage Property module: material editor: Use frequency-dependent data: Toggle on Nonlinear magnetic behaviorNonlinear magnetic behavior is characterized by magnetic permeability that depends on the strength of the magnetic field. The nonlinear magnetic material model in Abaqus is suitable for ideally soft magnetic materials without any hysteresis effects (see Figure 1) characterized by a monotonically increasing response in B–H space, where B and H refer to the strengths of the magnetic flux density vector and the magnetic field vector, respectively. Nonlinear magnetic behavior is defined through direct specification of one or more B–H curves that provide B as a function of H and, optionally, temperature and/or predefined field variables, in one or more directions. Nonlinear magnetic behavior can be isotropic, orthotropic, or transversely isotropic (which is a special case of the more general orthotropic behavior). More than one B–H curve is needed to define the nonlinear magnetic behavior if it is not isotropic. For each curve, the slope between the last pair of data points is assumed to be the permeability of the free space. Abaqus issues an error message if the slope between any two adjacent data points is less than 0.01 times the permeability of the free space, as computed based on the last two data points for that curve. Directional dependence of nonlinear magnetic behaviorIsotropic, orthotropic, or transversely isotropic nonlinear magnetic behavior can be defined. For non-isotropic nonlinear magnetic behavior a local orientation for the material directions must be specified (Orientations). Isotropic nonlinear magnetic behaviorFor isotropic nonlinear magnetic response only one B–H curve is needed at each temperature and field variable value. Isotropic magnetic permeability is the default. Abaqus assumes that the nonlinear magnetic behavior is governed by Input File Usage You define through a B–H curve: MAGNETIC PERMEABILITY, NONLINEAR, TYPE=ISOTROPIC NONLINEAR BH, DIR=direction The B–H curve in any direction (i.e., the nonlinear behavior in global direction 1, 2, or 3) will suffice as the nonlinear magnetic behavior is assumed to be the same in all directions. Abaqus/CAE Usage Property module: material editor: Specify using nonlinear B-H curve: Type: Isotropic: Toggle on Orthotropic nonlinear magnetic behaviorFor orthotropic nonlinear magnetic response three B–H curves (one curve to define the behavior in each of the local directions 1, 2, and 3) are needed at each temperature and field variable value. Abaqus assumes that the nonlinear magnetic behavior in the local material directions is governed by where refers to a diagonal matrix. Transversely isotropic nonlinear magnetic behavior is a special case of orthotropic behavior, in which the behavior in any two directions is the same and is different from that in the third direction. Input File Usage You define , , and , respectively, through three independent B–H curves, one in each of the directions 1, 2, and 3: MAGNETIC PERMEABILITY, NONLINEAR, TYPE=ORTHOTROPIC NONLINEAR BH, DIR=1 … NONLINEAR BH, DIR=2 … NONLINEAR BH, DIR=3 … Abaqus/CAE Usage Property module: material editor: Specify using nonlinear B-H curve: Type: Orthotropic: Toggle on Permanent magnetizationFerromagnetic materials can be magnetized by placing them in a magnetic field, which is typically created by applying currents in a system of coil windings surrounding the material being magnetized. These materials can be classified into soft and hard magnetic materials (see Figure 1). Soft magnetic materials lose their magnetization after removal of the applied currents (see Nonlinear magnetic behavior). Hard magnetic materials retain their magnetization permanently after removal of the applied currents. The leftover magnetization in a permanent magnet is called remanence, denoted by in Figure 2. This magnetization can be removed by applying currents in the opposite direction; the strength of the opposing magnetic fields that remove magnetization entirely is called coercivity, denoted by in Figure 2. Figure 1. Response of hard and soft magnetic materials.
Figure 2. Remanence and coercivity in permanent magnets.
Permanent magnetization in Abaqus is suitable for hard magnetic materials when the magnets are operating around the point of remanence. This behavior captures the response of magnetization or demagnetization around the point of remanence, as shown by the darker descending line of the hysteresis loop in Figure 2. The underlying magnetic permeability can be linear or nonlinear. In either case, permanent magnetization is defined by its coercivity such that for linear isotropic, orthotropic, or anisotropic magnetic behavior and for nonlinear isotropic - response. Input File Usage To specify permanent magnetization with underlying linear magnetic permeability: MAGNETIC PERMEABILITY PERMANENT MAGNETIZATION direction of magnetization in the global system magnitude of coercivity To specify permanent magnetization with underlying nonlinear magnetic permeability (nonlinear response of the left top portion of the hysteresis curve): MAGNETIC PERMEABILITY, NONLINEAR NONLINEAR BH input - by shifting the response to the right by PERMANENT MAGNETIZATION direction of magnetization in the global system magnitude of coercivity Abaqus/CAE Usage Permanent magnetization is not supported in Abaqus/CAE. ElementsMagnetic material behavior is active only in electromagnetic elements (see Choosing the appropriate element for an analysis type). |