signal-analysis

name	signal-analysis
description	Perform signal processing, rainflow cycle counting, and spectral analysis for fatigue and time series data. Use for analyzing stress time histories, computing FFT/PSD, extracting fatigue cycles (ASTM E1049-85), and batch processing OrcaFlex signals.
type	reference
updated	2026-01-07
capabilities	[]
requires	[]
tags	[]
scripts_exempt	true
category	engineering
version	1.0.0

Signal Analysis

When to Use

• Analyzing fatigue from stress/load time series
• Computing rainflow cycles for damage calculation
• FFT and power spectral density analysis
• Frequency spectrum characterization
• Batch processing OrcaFlex simulation signals
• Time series conditioning and filtering
• Converting time-domain data to frequency-domain

Prerequisites

• Python environment with digitalmodel package installed
• Time series data in CSV, Excel, or OrcaFlex format
• For OrcaFlex signals: completed .sim files

Python API

Rainflow Cycle Counting

from digitalmodel.signal_processing.signal_analysis.rainflow import RainflowCounter

# Initialize counter
counter = RainflowCounter()

# Load time history
import pandas as pd
data = pd.read_csv("stress_time_history.csv")
time = data["time"].values

*See sub-skills for full details.*
### Spectral Analysis

```python
from digitalmodel.signal_processing.signal_analysis.spectral import SpectralAnalyzer
import numpy as np

# Initialize analyzer
analyzer = SpectralAnalyzer()

# Load signal
data = pd.read_csv("motion_time_history.csv")
time = data["time"].values

*See sub-skills for full details.*
### Time Series Processing

```python
from digitalmodel.signal_processing.signal_analysis.time_series import TimeSeriesProcessor

# Initialize processor
processor = TimeSeriesProcessor()

# Load raw data
data = pd.read_csv("raw_signal.csv")
time = data["time"].values
signal = data["stress"].values

*See sub-skills for full details.*


```python
 digitalmodel.signal_processing.signal_analysis.orcaflex_signals  OrcaFlexSignalExtractor
 pathlib  Path


extractor = OrcaFlexSignalExtractor()


sim_file = Path()
time, tension = extractor.extract_time_history(

*See sub-skills  full details.*


```python
 digitalmodel.signal_processing.signal_analysis.readers  GenericTimeSeriesReader


reader = GenericTimeSeriesReader()


data = reader.read()



*See sub-skills  full details.*



- [fatigue-analysis](../fatigue-analysis/SKILL.md) - Use rainflow cycles  fatigue damage calculation
- [orcaflex/post-processing](../orcaflex/post-processing/SKILL.md) - Extract time histories  OrcaFlex
- [structural-analysis](../structural-analysis/SKILL.md) - Stress analysis  signal generation



- ASTM E1049-: Standard Practices  Cycle Counting  Fatigue Analysis
- Welch, P.D. (): The Use of FFT  Estimation of Power Spectra
- DNV-RP-C203: Fatigue Design of Offshore Steel Structures



- [Signal Quality (+)](signal-quality/SKILL.md)



- [Error Handling](error-handling/SKILL.md)



- [Version Metadata](version-metadata/SKILL.md)
- [[] - -01-07](--01-07/SKILL.md)
- [ Rainflow Cycle Counting (ASTM E1049-) (+)](-rainflow-cycle-counting-astm-e1049-/SKILL.md)
- [Complete Signal Analysis Workflow (+)](complete-signal-analysis-workflow/SKILL.md)
- [Rainflow Cycles CSV (+)](rainflow-cycles-csv/SKILL.md)