loadspectrum

Load spectrum, sometimes written as load spectrum data, is a representation of the distribution of loads that a component or structure experiences over time. It is used in fatigue and reliability analysis to summarize varying service conditions into a form suitable for life prediction, rather than relying on a single time history. The spectrum highlights how often different load levels occur and how severe they are, enabling more robust assessment of durability under real-world usage.

Construction and interpretation typically involve collecting load histories from field measurements, test rigs, or predefined duty cycles. The time-series data are processed with cycle-counting techniques, such as rainflow counting, to identify individual loading events and their amplitudes. The results are organized into a spectrum, often as a histogram or a function that relates cycle counts to corresponding load magnitudes. This representation can be used directly in fatigue calculations or converted to an equivalent load for simplified life estimation.

Applications span multiple engineering domains, including aerospace, automotive, civil engineering, and wind or marine structures. Load-spectrum analysis supports design optimization, maintenance planning, and reliability assessment by enabling cumulative damage estimates under realistic operating profiles. It is distinct from a simple load profile, as it emphasizes the statistical distribution of load magnitudes and frequencies rather than just instantaneous values. Uncertainties in measurements, material properties, and modeling assumptions are important considerations in interpreting a load-spectrum-based life prediction.