Dimensionless heat transfer model to compress and analyze pulsed thermography data for NDT of materials

摘要

We develop a dimensionless heat transfer model to analyze pulsed thermography data for non-destructive testing (NDT)of materials. Simulated thermographic sequences are used in order to evaluate the performance of the inspectiontechnique. Also, we inspect organic and inorganic samples, including a layered plate and two dental pieces, in search ofinternal defects and structural inhomogeneities. We detect cavities and the inner structure of the samples by means of reconstructed thermograms and a modified version of the differential absolute contrast (DAC). Moreover, we developan effective data compression method that reduces a thermographic video with m frames of p x q pixels to two matrices of p x q elements. In this data reconstruction process, precision and compression ratio are independent parameters.Finally, we find that partial translucency of dental enamel, in infrared, permits imaging of the internal structure of atooth. This inspection technique does not require a priori knowledge about a reference defect-free area.