Q2. What is the common example of forged axles?
In the case of forged axles, the macroscopic stress gradients resulting from the external load can be superimposed to microstructural ones, for instance varying grain size in the width of the axle.
Q3. Why are forged axles a typical application of fatigue?
Due to their loading in rotatory bending, which is in general superimposed in the most critical areas to a local stress gradient induced by notches, they are a typical application of fatigue in the presence of gradients.
Q4. What is the way to account for small clusters effects?
The use of macroscopic constitutive laws parameterized with grain size at the grain scale, although not realistic to describe intragranular fields, is a very simple and efficient way to account for such small clusters effects.
Q5. What is the common category of fatigue studies?
The first category is predominant in fatigue studies, and has accumulated significant results, such as the relative importance of elastic anisotropy and crystal plasticity on FIP distributions [16,17], or the importance of local grain cluster effects [18] on individual grain responses.
Q6. What is the way to assess the mechanical response of polycrystalline aggregates under stress gradients?
In order to qualitatively assess the mechanical response of polycrystalline aggregates under macroscopical stress gradients, a solution is to place the microstructural gradients at the root of a notched specimen.
Q7. What is the average stress of the A1 aggregate?
The load giving an average stress of 270 MPa (mean yield strength for A1) over the 1 mm 1 mm patch in the notch root is considered as the fatigue limit of the A1 aggregate.
Q8. how does the tessellation of the grain yield strength be calculated?
This leads to distribute yield strengths over the aggregate in the three following steps (Fig. 3):The draw is done from a Gaussian distribution, of mean value ry;g , and the standard deviation is taken identical to that of the yield strength distribution given by the Hall–Petch law for a Poisson-Voronoi tessellation of representative grain size.