Stress - Vibrationdata Engineering Blog

Flow Stress: A Unifying Parameter in Fatigue and Fracture Analysis

July 19, 2026June 30, 2026 by Tom Irvine

Introduction Flow stress is one of those quantities that shows up everywhere in structural metals engineering, yet it rarely gets the dedicated treatment that stress intensity factor, S-N curves, or fatigue strength coefficients receive. It appears quietly in cyclic plasticity models, in fracture toughness test… Read more

Why Steel Yields the Way It Does: Lüders Bands and the Yield Plateau

July 23, 2026June 7, 2026 by Tom Irvine

VibrationData Blog | Structural Materials If you have ever looked at a stress-strain curve for mild (low-carbon) steel and wondered why it has that distinctive “flat shelf” between the upper and lower yield points, you are not alone. That plateau is one of the most… Read more

Dynamic vs. Static Moduli — Practical Considerations for Structural Dynamics

July 23, 2026June 5, 2026 by Tom Irvine

Dynamic Versus Static Modulus: Why ASTM E1876 and ASTM E111 Don’t Always Agree Engineers frequently encounter situations where material properties reported in handbooks don’t quite match experimental data. A classic example occurs when comparing elastic modulus values obtained from different test standards. When evaluating stiffness,… Read more

Stress Concentration Factor & Crack Initiation

July 19, 2026March 28, 2021 by admin

This photo was taken outside of my former office in Huntsville, Alabama. As newly poured concrete hardens and dries, it shrinks. This is due to the evaporation of excess mixing water. The cracks in the photo may have formed during this phase. In addition, the concrete experiences… Read more

Material Shock Loading

July 19, 2026July 20, 2020 by admin

The plot shows the applied strain on the horizontal axis and the resisting stress on the vertical axis. The area inside the triangle represents the maximum energy that can be absorbed elastically, if the member is strained up to its proportional limit stress. The member… Read more

Kinetic & Strain Energy Formulas

July 20, 2026February 3, 2016 by admin

Kinetic & strain energy formulas can be used as a basis for Rayleigh-Ritz or finite element analysis of vibrating structures. Equations for common structures and loading conditions are given in strain_energy.pdf The cases include: Uniform Bar under a Constant Axial Load Bar under a General Axial… Read more