Fatigue Monitoring of a Dented Piping Specimen Using Infrared Thermography

Abstract

The present paper combines the fatigue properties rapid assessment approach using uniaxial test specimens proposed by Risitano and co-workers with the nondestructive testing (NDT) inspection approach proposed by Sakagami and co-workers to monitor the onset of fatigue in a reduced scale pipeline test specimen that was previously dented and subsequently subjected to cyclic pressure loading. In addition to the use of the conventional infrared (IR) thermographic method, the present paper uses a self-reference lock-in IR thermography method based on Thermoelastic Stress Analysis (TSA) and its deviation from traditional applications due to the presence of fatigue damage and plastic strains. The paper concludes showing that is possible to predict and monitor and detect fatigue initiation and damage using IR and TSA techniques applied to the thin wall pipe loaded under cyclic hydrostatic pressure.

Fatigue Tests on Buried or Repaired Dented Steel Pipeline Specimens

“…Fiber Optic Bragg Strain Gauge sensors were bonded to the hot-spot locations at the specimens' dented external surfaces to collect strain information during testing. Based on findings presented by [9,12], the circumferential strains are considerably higher compared to longitudinal strains, and the circumferential strain range was assumed to be representative of the specimen's fatigue behavior. Moreover, in most cases the longitudinal strains showed negligible or even small compressive magnitudes when the hot spots were loaded under elastic-plastic conditions, due to the need for constant volume plasticity deformation [12].…”

“…The fatigue behavior of pipeline specimens with dents under cyclic internal pressure loading, with and without restriction constraints to free deformation, have been studied by different researchers (e.g., see [1][2][3][4][5][6][7][8][9]). Although dent depth criteria are the most frequently used in the industry for their ease of application, the determination of cyclic strains operating on the dent hot spots are needed to enhance the accuracy of fatigue life predictions.…”

Modern Experimental Techniques With an Emphasis on Infrared Thermography to the Assessment of Fatigue Components With Dents

“…Paiva et al [59][60][61][62][63][64] conduct an investigation program to assess pipeline specimens containing dent defects using IR thermography. In these cases, the component behavior was evaluated, and the material properties were quantified using the thermal response.…”

“…Paiva et al [59,60,61,92,93] studied the behavior of re-rounded dents using a strain-life approach. These references conducted an experimental investigation using DIC coupled with FEA to determine the actual dent shape and strain distributions over the deformed regions.…”

Avaliação De Componentes Sob Carregamento Quase Estático Usando Termografia Por Infravermelho

“…Na Tabela 3.2 foi aplicada a mesma nomenclatura do Paiva (2020) para facilitar as comparações dos resultados obtidos nesta dissertação. O espécime 3 foi utilizado para monitoramento da fadiga através da TIV,Paiva et al (2018). Ela não foi estudada neste trabalho.PUC-Rio -Certificação Digital Nº 1821040/CA…”