Thermoelastic Stress and Damage Analysis Using Transient Loading

Abstract

Response to reviewers' commentsWe thank the referees for the time they have spent reviewing our paper and for providing us with some helpful comments which have improved the quality of the paper. We have responded to each comment in turn below and highlighted the manuscript in yellow to indicate where the changes have been made.Reviewer #1: This papers looks at a variation on thermoelastic stress analysis in which instead of using cyclic loading and lock-in amplification either a single step load or an impact load are used. In either case a dynamic stress field is created, and for short durations the associated thermal problem is approximately adiabatic, resulting in measurable temperature field changes. The point of the work is to demonstrate thermoelastic stress analysis as an NDE technique that might complement or compete with flash thermography or high frequency, vibration induced heating of cracks in structures.The paper is OK, but could and should be improved. Figures 3 and 4 should have a time scale on them. 1. Done.It would also be useful to indicate the framing rate of the IR camera for this data.Added at top of page 4.2. There is a difference between the theoretical, TSA, step and impact loading temeperatures, figures 6-9. The authors brush this off as experimental error, but the difference is always there and in the same direction -lower.We do not brush this off as experimental error. Instead we have provided detailed discussion in the original text as follows:On the standard test, this is covered on page 8/9 and centres on the assumed emissivity value. The difference in the scatter in the 2.5 Hz and 20 Hz measurement is explained on page 9.The step loading case in discussed on page 9 and it is highlighted that there is a lower stress limit for which viable readings can be obtained. Response to Reviewer CommentsFor the impulse test (Figs 8 and 9) we say that the difference cannot be attributed to emissivity alone -we highlight potential sources of errors in the clamping arrangement and we mention the possibility of heat dissipation -see bottom of page 10.It is likely that the process is not entirely fast enough to neglect conduction of heat.This does not mean that the method will not work, but perhaps the proposed approach must be coupled to transient heat conduction calculations in order to be quantitative about the measured stress levels.The authors agree with the reviewer's comment that heat transfer is an important consideration when testing at low frequencies, and that this was perhaps not given sufficient emphasis in the original submission. However, in uniaxial tension tests (Figures 6 & 7), where the stress and hence temperature gradients are small (or nominally zero in the UD case), non-adiabatic effects do not provide a sufficient explanation. Hence the experimental errors, for example estimates of the surface emissivity and the material properties (i.e. density, heat capacity, CTE…) are sought to explain the discrepancy (top of page 9). In the bending case (Figures 8 & 9), stress gradients ...

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