Fatigue crack propagation in polycarbonate foam

Multidiscipline Modeling in Materials and Structures

2015

Purpose -The purpose of this paper is to study theoretically the ability of the prestressed foam core composite sandwich Split Cantilever Beam (SCB) for generating mixed-mode II/III crack loading conditions (the mode II fracture was provided by prestressing the beam using imposed transverse displacements). Design/methodology/approach -The concepts of linear-elastic fracture mechanics were used. The fracture behavior was studied in terms of the strain energy release rate. For this purpose, a three-dimensional finite element model of the prestressed sandwich SCB was developed. The virtual crack closure technique was applied in order to analyze the strain energy release rate mode components distribution along the crack front. Findings -It was found that the distribution is non-symmetric. The analysis revealed that a wide mixed-mode II/III ratios range can be generated by varying the magnitude of the imposed transverse displacement. The influence of the sandwich core material on the mixed-mode II/III fracture behavior was investigated. For this purpose, three sandwich beam configurations with different rigid cellular foam core were simulated. It was found that the strain energy release rate decreases when the foam core density increases. Originality/value -For the first time, a mixed-mode II/III fracture study of foam core composite sandwich beam is performed.

Section: Introductionmentioning

confidence: 99%

Analysis of mixed-mode II/III fracture in sandwich beams

Multidiscipline Modeling in Materials and Structures

2015

“…Fatigue fracture behavior of foam core materials has been characterized using the Paris' law equation [7]. Yau and Mayer have investigated the environmental effects on the fatigue crack growth rates in Polycarbonate foam material [8].…”

Section: Introductionmentioning

confidence: 99%

Fracture in foam core composite sandwich beams under mixed-mode I/II/III loading conditions

Strength, Fracture and Complexity

2014

Static fracture in foam core composite sandwich beams under mixed-mode I/II/III crack loading conditions is studied theoretically by the Mixed Mode Flexure (MMF) beam configuration. The basic idea of this paper is that mixed-mode I/II/III crack loading conditions can be generated by loading the MMF sandwich beam by an inclined force (usually, the MMF beam, loaded by a vertical force, is used for investigating mixed-mode I/II fracture in continuously fiber reinforced polymer composites). Three-dimensional finite element simulations of the MMF sandwich beam are performed using the ANSYS program system. The methods of linear-elastic fracture mechanics are applied. The fracture behavior is studied in terms of the strain energy release rate. The virtual crack closure technique is applied to analyze the strain energy release rate mode components distribution along the crack front in the MMF beam at the force inclination varying from 0 • (force parallel to the crack front) to 90 • (vertical force). The analysis revealed that the MMF beam loaded by an inclined force can be used to study the mixed-mode I/II/III fracture in foam core composite sandwich beams over wide mixed-mode ratios ranges.

“…Results from static fracture analysis of foam cores have been presented in [1]. Fatigue fracture 14 V. Rizov / Fracture study of rigid foam using single edge notched bend specimens with inclined notch behavior of foam materials has been studied in [2,3]. The fatigue crack growth rates have been related to the cyclic stress intensity factor range using the Paris' law equation [2].…”

Section: Introductionmentioning

confidence: 99%

“…The fatigue crack growth rates have been related to the cyclic stress intensity factor range using the Paris' law equation [2]. The environmental effects on the fracture have been analyzed by You and Mayer [3]. Mode III fracture behavior of rigid foams has been investigated using an anti-clastic plate bending test method by Farshad and Flüeler [4].…”

Section: Introductionmentioning

confidence: 99%

Fracture study of rigid foam using single edge notched bend specimens with inclined notch

Strength, Fracture and Complexity

2013

This paper presents results from a study of fracture behavior of rigid foam. Various mixed-modes I/II loading conditions were generated by the aid of single edge notched three point bending (SENB) test specimens containing an inclined notch as an initial crack. Three-dimensional finite element models of the SENB specimens were developed for analyzing the fracture test data. From the experimentally measured crack growth initiation loads various mixed-mode I/II critical strain energy release rates were computed by the virtual crack closure technique. The analysis revealed that besides mode I and mode II, there was also insignificant mode III component of the critical strain energy release rate. The variation of the critical strain energy release rate mode components with increase of the notch inclination was studied. It was found that the relative amount of the mode II component progressively decreases with increasing the notch inclination. It was concluded that the considered version of the SENB test specimen can be used for investigating fracture behavior of rigid foams in a function of the mixed-mode ratio over an interval of 0 G a IIC /G a C 0.413. It was found also that the theory of Sih can be applied successfully for analysis of mixed-mode I/II fracture in rigid foams.