Project

Thermographic camera with a set of lenses, including specific software for thermo-elastic stress analysis

Code
01B09412
Duration
15 June 2012 → 30 June 2016
Funding
Regional and community funding: Special Research Fund
Research disciplines
  • Engineering and technology
    • Destructive and non-destructive testing of materials
Keywords
Thermography
 
Project description

  What is the stress distribution near the surface of a component during fretting-fatigue? Two components that are in contact with each other and of which é é n is subjected to a varying load, may fail due to a combination of surface wear (fretting), and fatigue. To the creation and assess the evolution of the damage mechanisms, knowledge of the tension near the surface in the fretting contact of enormous importance. Analytical and numerical models developed to predict in terms of the geometry of the contact and the applied loads these tensions and their relationship to surface wear and tear initiation. These quantities are not directly measurable in experiments on coupons. Attempts to validate the models by indirect experimental measurements of related quantities such as eg. Micro-slip between the two components would be insufficient. How do crack initiation and crack propagation in the overall fatigue life of a component? The prediction of the fatigue life of a component requires an analytical description of crack initiation and crack propagation. Different models give rise to very different results. Moreover, there is no consensus on the boundary between initiation and propagation. Through post-mortem evaluation of a sample failed the course of crack propagation can be estimated. An online experimental evaluation of crack initiation and propagation, however, is currently impossible. Attempts to estimate this via indirect measurements (local deformations on the surface or overall shape changes), are not sufficient. What is the effect of material heterogeneity and material defects on the deformation behavior of welded joints? In numerical models are welding ISOLATED dealiseerd as homogeneous materials. The complex microstructure which arises as a result of the heat cycles during the welding process, gives rise to variation in the mechanical properties of the weld metal and heat-be & iuml; nvloede zone. Under load, into the plastic zone this will lead to non-uniform deformations. Also when welding small '' invisible '' errors (inclusions or porosity) which occur under load will lead to highly localized deformations or damage. Optical measurements only allow to visualize the deformations at the surface. What is the evolution of ductile crack growth in global plastic deformation? If a component with notch is subjected to a global plastic deformation, stable crack extension will occur to those of notch. The failure mode of the component is governed by the progress of the crack propagation. Numerical models were developed to predict the crack propagation. An experimental measurement of this is currently not possible, and experimental validation, therefore, is carried out by correlation with a measurement of the gap between the crack fronts. However, a generic correlation is apparent non-existent. What is the proportion of thermal effects in the friction and wear of polymers,? The friction and wear of polymers is determined by mechanical (deformation, abrasion) and physicochemical (adhesion, melting) mechanisms. Both are partly be & iuml; influenced by the effective temperature as a result of dissipation of frictional heat in the contact. Measuring the contact temperature is impossible so to speak. The best approach is to measure the temperature field near the contact. These questions require an experimental equipment must meet different requirements. The device should be deployed in a variety of laboratory set-ups in which measurements are to be performed during static, quasi-static and dynamic experiments. The measurement areas ranging & euml; run of about 10mm to 10mm during wear and fretting experiments (spatial resolution of 0.01mm is required) to 150mm to 150mm during fatigue and ductile fracture propagation (spatial resolution of 0.05 mm is required) and are not necessarily stable in space . Both visually accessible and inaccessible phenomena to be mapped. The measurement should be non-destructive and contactless. A thermographic camera makes it possible very accurately, both spatially and in time, to measure temperatures at and near the surface of a component. Heat dissipation is caused by phenoma as frictional, elastic, and plastic deformations (thermo elastic and thermoplastic effect), damage development and expansion, materiaalinhomogeniteiten. A literature review has shown that thermographic cameras are used worldwide for research activities related to the above research.