This paper evaluates the effects of microbiologically influenced corrosion (MIC) on fatigue-crack growth of candidate materials useful in expanding bio-ethanol usage, including a storage-tank steel (ASTM A36) and two pipeline steels (API 5L X52 and X70). The microbiological species sampled and cultivated from an ethanol fuel production stream are responsible for both acetic acid and hydrogen su...

A cohesive fatigue-crack nucleation and growth model for ferroelectric materials under electro-mechanical loading is presented. The central feature of the model is a hysteretic cohesive law which couples the mechanical and electrical fields. This law can be used in conjunction with general constitutive relations of bulk behavior, possibly including domain switching, in order to predict fatigue ...

In the present note, the effects of two typical organic solvents, ethanol (95~) and carbon tetrachloride (99~) , on the fatigue crack propagation rates in PMMA are discussed. Fracture mechanics which has been applied successfully to fatigue crack propagat ion in bo th metallic and polymeric sheet materials [1-4] in air is adopted in the present environmental fatigue analyses. The generalized fa...

This research comprises a study of the effect of heat treatment on fatigue behavior of (A193-51T-B7) alloy steel. Two heat treatment processes were conducted, namely, annealing and quenching followed by tempering at 200C. All fatigue tests were carried out using a rotary bending machine with constant stress ratio, R=-1. The eddy current probe was used to measure the crack length propagation. Fr...

A model has been created to allow the quantitative estimation of the fatigue crack growth rate in steels as a function of mechanical properties, test–specimen characteristics, stress–intensity range and test–frequency. With this design, the remarkable result is that the method which is based on steels, can be used without modification, and without any prior fatigue test, to estimate the crack g...

In the present investigation, an attempt has been made to use “exponential model” in the prediction of fatigue life without integrating the fatigue crack growth rate curve (FCGR). The obtained results are compared with experimental crack growth data obtained for 2024-T351 aluminum alloy for four bending V-Charpy specimens under constant amplitude loading in stress ratio range from 0.1 to 0.3 an...

The fatigue growth of a fiber reinforced composite laminate was characterized under thermal cycling using a combined experimental and computational investigation. Twenty-four ply composite laminates (1⁄20 12=90 12 ) are fabricated with a pre-existing delamination, and subjected to thermal cycling in an environmental chamber. The large mismatch in the coefficients of thermal expansion is used to...

A major part of fracture mechanics is concerned with studying the initiation and propagation of fatigue cracks. This typically requires constant monitoring of crack growth during fatigue cycles and the knowledge of the precise location of the crack tip at any given time. One technique currently available for measuring fatigue crack length is the Potential Drop method[1]. The method, however, ma...

Fatigue crack growth can be strongly influenced by crack closure, i. e., the contacting of the opposing faces of a fatigue crack above the minimum load in a loading cycle. This crack closure shields the crack tip from the full stress field, but different views are held regarding the extent of this shielding. The type of closure, whether it be plasticity-induced, or roughness-induced may also pl...

Understanding the fatigue crack growth phenomenon in railheads requires a study of driving forces such as the crack tip opening and sliding displacements, under repeated rolling contact. Finite element simulations, allowing elastic-plastic deformation, and mixed-mode crack growth laws were utilized to demonstrate that the fatigue crack growth rates display a minimum after a finite amount of cra...