Customize DesignLife and design up-front by selecting from a number of modules designed to help you streamline your CAE durability process. Gain flexible access to product options and use only when you need them by leveraging token-based licensing.
The primary application of the Stress-Life (SN) method is high-cycle fatigue (long lives) where nominal stress controls the fatigue life. Includes the ability to interpolate multiple material data curves for factors such as mean stress or temperature. Further options are also provided to account for stress gradients and surface finishes. Python scripting is also available for defining custom fatigue methods and material models.
The Strain-Life method is applicable to a wide range of problems including low-cycle fatigue with the local elastic-plastic strain controls the fatigue life. The standard EN method uses the Coffin-Manson-Basquin formula, defining the relationship between strain amplitude εª and the number of cycles to failure Nf. Material models can also be defined using general look-up curves. This enables the ability to interpolate multiple material data curves for factors such as mean stress or temperature.
Dang Van is a multi-axial fatigue limit criterion and is a method of predicting the endurance limit under complex loading situations. The output from the analysis is expressed as a safety factor rather than fatigue life.
Safety Factor enables the calculation of stress based factors of safety. This method is widely used as a key design criteria for engine and powertrain components like crankshafts, camshafts and pistons.
The Spot Weld option enables the fatigue analysis of spot welds in thin sheets. The approach is based on the LBF method (see SAE paper 950711) and is well-suited to vehicle structure applications.
DesignLife simplifies the process of setting up fatigue analysis of seam welds by intelligently identifying weld lines in an FE model. The Seam Weld option enables the fatigue analysis of seam welded joints including fillet, overlap, and laser welded joints. The method is based on the approach developed by Volvo (see also SAE paper 982311) and validated through years of use on vehicle chassis and body development projects.
The methods used in the WholeLife option improves the accuracy of analysis of thick welds. It uses an integrated approach for modeling fatigue over the entire lifetime of a component - from the very early stages to final fracture - to give more accurate determination of weld lives particularly for complex geometries. The same structural stress technique used for seam welds is used in WholeLife to determine the structural bending and membrane stresses at the weld.
WholeLife uses the through thickness stress distribution for the geometry and can include the effect of a known residual stress profile. Although this is primarily a CAE based analysis, the same method may also be applied to measured stress data.
The Vibration Fatigue option provides the capability to predict fatigue in the frequency domain and it is more realistic and efficient than time-domain analysis for applications with random loading such as wind and wave loads or where structures are excited by rotating machinery.
Read the article: Three virtual vibration fatigue scenarios you should know about
Applications: Vehicle electrification - identify the critical fatigue failure points on all types of battery structure, materials, welds, and joining technologies
Video: Introduction to nCode DesignLife for Frequency Domain Fatigue
Video: How to design an optimized vibration test for battery packs
Video: Tips and Tricks for Understanding Vibration Fatigue in nCode DesignLife
The Thermo-Mechanical Fatigue (TMF) option provides solvers for high temperature fatigue and creep by using stress and temperature results from finite element simulations. Mechanical loads that vary at a different rate to the temperature variations can also be combined. Applications include components that are both mechanically and thermally loaded such as vehicle exhaust systems and manifolds.
High temperature fatigue methods:
Creep analysis methods:
The Short Fibre Composite option uses stress-life fatigue calculations for anisotropic materials such as glass fibre filled thermoplastics. The stress tensor for each layer and section integration point through the thickness is read by DesignLife from FE results. The material orientation tensor describing the “fibre share” at each calculation point is provided by mapping a manufacturing simulation to the finite element model. This orientation tensor can be read from the FE-results file or supplied from an ASCII file.
Short Fibre Composite module features:
The Composite Analysis option allows users to evaluate the strength of a structure against industry standard composite failure criteria. Rather than limiting this evaluation to a small number of load cases or steps, stresses can be assessed by using the chosen failure criteria throughout realistic duty cycles (quasi-static or dynamic). This allows critical locations, load combinations and associated design reserve factors to be readily identified. In addition, selected location loading paths may be visually compared with the material failure envelope.
The following methods can be used individually or combined to give the most conservative result:
The Strain Gauge Positioning option calculates the optimum position and number of gauges required to enable the subsequent reconstruction of applied load histories.
The Loads Reconstruction glyph uses the virtual strains created by unit loads along with the measured strain histories from gauges matching the virtual strain gauges to reconstruct the force histories that caused the measured strains.
nCode DesignLife uses a fracture mechanics-based method to assess which joints in the structure are most critically loaded. The Adhesive Bonds option enables durability calculations on adhesive joints in metallic structures.
Distributed Processing enables a DesignLife analysis running in batch mode to be distributed across multiple computers or nodes of a computer cluster.
Processing threads enable you to get finished results from raw inputs in faster. DesignLife can parallel process on machines with multiple processors, each Processing Thread license allowing another core to be utilized. Since the fatigue calculation at each model location is effectively independent, the benefit to adding additional processing threads is very scalable. Multiple threads can also be used to speed up the translation phase of the analysis by splitting the translation into multiple processes.