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Fatigue
Fatigue analysis is intended for predicting life of structures under cyclic loading.
Fatigue Theory
Background information on Fatigue analysis in SimSolid.
Damage Accumulation Model
Palmgren-Miner's linear damage summation rule is used.

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- Structural
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- Dynamics
  Evaluate your design in real-time using SimSolid dynamics analysis.
- Thermal
  Thermal analysis predicts how thermal effects propagate through the model. Steady state and thermal transient analyses are supported.
- Fatigue
  Fatigue analysis is intended for predicting life of structures under cyclic loading.
  - Fatigue Theory
    Background information on Fatigue analysis in SimSolid.
    - Fatigue Assessment Methods
      In SimSolid, uniaxial and multiaxial fatigue analysis using SN (stress-life) and EN (strain-life) approach is supported.
    - Stress-life (SN) Approach
      The stress-life method works well in predicting fatigue life when the stress level in the structure falls mostly in the elastic range.
    - Strain-life (EN) Approach
      The EN Approach uses plastic-elastic strain results to perform strain-life analysis.
    - Spot Weld Fatigue Analysis
      Allows for the study of fatigue performance of spot welds in structures.
    - Seam Weld Fatigue
      The seam weld fatigue implemented in SimSolid is based on linearization of stress in the conjunction with Volvo method and following that it predicts fatigue damage and life. Linearized stress decomposes a through-thickness elastic stress field into equivalent membrane and bending.
    - Random Response Fatigue Analysis
      The study of fatigue life of structures under random loading.
    - Rainflow Cycle Counting
      Use cycle counting to extract discrete simple "equivalent" constant amplitude cycles from a random loading sequence.
    - Mean Stress Correction
      Use mean stress correction to account for the effect of non-zero mean stresses.
    - Damage Accumulation Model
      Palmgren-Miner's linear damage summation rule is used.
    - Endurance Limit Modifying Factors
      Account for factors that can affect fatigue strength of a structure.
    - Scatter in Fatigue Material Data
      Handle scatter in fatigue test results.
  - Import Loadcase-channel Map
    Import a loadcase-channel map file to import all the channels defined in the file and create appropriate events.
  - Import Channels
    Import channels which define load amplitude changes in time.
  - Review Channels
    Review channels in a group.
  - Create Event
    Create an event consisting of channels and loadcases.
  - Import Sequences
    Import a file to automatically create load case sequences.
  - Create Sequence
    Create a sequence with load cases for the fatigue analysis.
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Damage Accumulation Model

Palmgren-Miner's linear damage summation rule is used.

Failure is predicted when:

(4)

\sum D_{i} = \sum \frac{n_{i}}{N_{i f}} \geq 1.0

Where:

$N_{i f}$ is the material’s fatigue life (number of cycles to failure) from its SN curve at a combination of stress amplitude and means stress level $i$
$n_{i}$ is the number of stress cycles at load level $i$
$D_{i}$ is the cumulative damage under the $n_{i}$ load cycle.

The linear damage summation rule does not take into account the effect of the load sequence on the accumulation of damage due to cyclic fatigue loading. However, it has been proved to work well for many applications.