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Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy.

Withers PJ - Philos Trans A Math Phys Eng Sci (2015)

Bottom Line: X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces.Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure.It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement.

View Article: PubMed Central - PubMed

Affiliation: Manchester X-ray Imaging Facility, School of Materials, Manchester University, Manchester M13 9PL, UK Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK p.j.withers@manchester.ac.uk.

ABSTRACT
To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored.

No MeSH data available.


Related in: MedlinePlus

(a) Crack-opening strain, εyy, profile along the crack plane (y=0) at the centre of a 15 mm thick bainitic steel CT sample at Kmax (solid line) and Kmin (dashed line; ΔK=28 MPa√m; R ratio=0.05) as a function of the number of cycles after a 100% overload (OL) event. (b) The same data plotted as the difference in elastic strain between Kmax and Kmin as a function of the number of cycles. The arrow shows the location of the extensive plastic deformation from the overload event [36]. (Online version in colour.)
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RSTA20130157F8: (a) Crack-opening strain, εyy, profile along the crack plane (y=0) at the centre of a 15 mm thick bainitic steel CT sample at Kmax (solid line) and Kmin (dashed line; ΔK=28 MPa√m; R ratio=0.05) as a function of the number of cycles after a 100% overload (OL) event. (b) The same data plotted as the difference in elastic strain between Kmax and Kmin as a function of the number of cycles. The arrow shows the location of the extensive plastic deformation from the overload event [36]. (Online version in colour.)

Mentions: In principle, diffraction provides a means of quantifying crack-face closure contact stresses. An example is provided by Lopez-Crespo et al. [36], who measured a series of line scans along the crack plane to follow the progress of the crack-tip elastic strain field (crack-opening strain) with number of cycles before, and after, a 100% overload (figure 8).Figure 8.


Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy.

Withers PJ - Philos Trans A Math Phys Eng Sci (2015)

(a) Crack-opening strain, εyy, profile along the crack plane (y=0) at the centre of a 15 mm thick bainitic steel CT sample at Kmax (solid line) and Kmin (dashed line; ΔK=28 MPa√m; R ratio=0.05) as a function of the number of cycles after a 100% overload (OL) event. (b) The same data plotted as the difference in elastic strain between Kmax and Kmin as a function of the number of cycles. The arrow shows the location of the extensive plastic deformation from the overload event [36]. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308984&req=5

RSTA20130157F8: (a) Crack-opening strain, εyy, profile along the crack plane (y=0) at the centre of a 15 mm thick bainitic steel CT sample at Kmax (solid line) and Kmin (dashed line; ΔK=28 MPa√m; R ratio=0.05) as a function of the number of cycles after a 100% overload (OL) event. (b) The same data plotted as the difference in elastic strain between Kmax and Kmin as a function of the number of cycles. The arrow shows the location of the extensive plastic deformation from the overload event [36]. (Online version in colour.)
Mentions: In principle, diffraction provides a means of quantifying crack-face closure contact stresses. An example is provided by Lopez-Crespo et al. [36], who measured a series of line scans along the crack plane to follow the progress of the crack-tip elastic strain field (crack-opening strain) with number of cycles before, and after, a 100% overload (figure 8).Figure 8.

Bottom Line: X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces.Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure.It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement.

View Article: PubMed Central - PubMed

Affiliation: Manchester X-ray Imaging Facility, School of Materials, Manchester University, Manchester M13 9PL, UK Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK p.j.withers@manchester.ac.uk.

ABSTRACT
To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored.

No MeSH data available.


Related in: MedlinePlus