Endurica CL received many improvements over the past year. These improvements cover a wide variety of different aspects of the software:
Our investments in code benchmarking and performance are paying off! We’ve been able to make internal optimizations to the code that reduce analysis run-times by approximately 30%.
HFM and HFO Formatting
To make our output cleaner and more meaningful, small changes have been made to the number formatting in the HFM and HFO files.
All results reported in scientific notation are now formatted in standard form where the leading digit before the decimal point is non-zero (previously the leading digit was always zero). This gives one more significant figure to all the results without increasing the output file size.
The shortest fatigue life for the analysis is now printed to the console and HFM file with six significant figures. Previously, the life was reported with only two significant figures. This change makes it easier to quickly compare two different analyses, especially when the analyses have similar fatigue lives.
New features have been added to Endurica CL to make it easier to process and analyze histories. Using the new COMPRESS_HISTORY output request, you can generate new HFI files containing compressed versions of your original history. The generated history is composed of the rainflow counted cycles from your original history. An optional output parameter allows you to further compress the signal by specifying the minimum percentage of the original damage that should be retained in the new history. When keeping a percentage of the damage, the cycles are sorted from most to least damaging so that the generated history always contains the most damaging cycles and discards the least damaging cycles.
This output request is useful when you want to reduce a long complex history while keeping the important damaging cycles. This can reduce file sizes and simplify experimental testing setups as well as give you a deeper insight into your duty cycle.
Endurica DT is our incremental fatigue solver. With Endurica CL, your analysis starts at time zero and integrates the given strain history until end-of-life. With Endurica DT, you can start and end at a series of times that you specify. This lets you accumulate many different histories and loading conditions repeatedly until end-of-life.
Endurica DT gives you new ways to control your analyses, and we have been using it over the past year in many applications. For example, fatigue results for laboratory test procedures that involve multiple loading stages (such as FMVSS No. 139 for light vehicle tires, or block cycle schedules for automotive component applications) can be fully simulated using Endurica DT. You can also compute residual life following some scheduled set of load cases.
Endurica DT can also be used to accumulate the actual loads measured on a part in situ. This allows you to create a digital twin that keeps a near real-time record of the part’s current simulated damage state and the part’s remaining fatigue life.
Stiffness Loss Co-Simulation
Endurica DT now includes a stiffness loss co-simulation workflow that allows you to iteratively update the stiffness of your part over a series of time steps, based on the amount of damage occurring in the part. The stiffness loss is computed per element so you will have a gradient where the more damaged regions become softer. Endurica DT computes the current fraction h of stiffness loss based on the stress and strain, and the finite element solver computes the stress and strain based on the current fractions of stiffness loss. The capability accurately predicts the effects of changing mode of control during a fatigue test. For example, stress controlled fatigue tests show shorter life than strain controlled fatigue tests.
Endurica EIE, our efficient interpolation engine, quickly generates long, complex histories using a set of precomputed finite element results (i.e. the ‘nonlinear map’). We first launched EIE last year with the ability to interpolate 1-channel and 2-channel problems. We have recently added the ability to interpolate 3-channel problems.
In the example below, EIE was benchmarked with three-channels. Three separate road load signals were computed from a single nonlinear map. With EIE, you don’t need to rerun the finite element model for each history. Instead, EIE interpolates from the nonlinear map, providing the equivalent results with a 60x speed-up in compute time.