Termograficzne pomiary okładzin ciernych hamulców

Opracowanie nowej generacji hamulców wymaga wykonania pomiarów rozkładów temperatury na powierzchniach jego elementów konstrukcyjnych. W pracy przedstawiono wybrane wyniki takich badań metodami termograficznymi. W rezultacie tych badań określono obszary o podwyższonej temperaturze, temperaturę maksymalną oraz szybkość zmian temperatury. Porównano otrzymane wyniki z pomiarami metodą stykową. Dane otrzymane w wyniku analizy termogramów pozwolą na weryfikację modelu numerycznego hamulca.

Braking process has rather short duration (5s÷15s) and during that time the kinetic energy of a vehicle is transformed into heat. Such amount of heat generates thermal shock to braking pads and discs. Development of a new type of brakes requires measuring temperature distributions on their working surfaces. The paper presents some selected results of such measurements performed on a modified IL-68 test rig by means of thermal imaging (Fig. 2). Two types of composite braking pad materials were tested: C/C and 500/EBC. C/C composite is used for aircraft brakes, whereas 500/EBC type is used for brakes of all-terrain ground vehicles. Due to high dynamics of the thermal signal, the measurements were taken in the range from 200?C to 750?C. The data from the thermal images were processed using IR Control software. As a result there were identified the high temperature areas (hot spots), maximum temperature values for each recorded frame and the rate of temperature changes during braking (Fig. 5) as well as cooling down (Fig. 6) phases. The frame-by-frame analysis of the recorded thermal image sequences made it possible to correlate the temperature distribution non-uniformity with structural defects of the tested brake pads. The results of temperature measurements were compared with those obtained from the contact method (Fig. 7). On that basis, the errors of non-contact temperature measurements were estimated. The analysis of the recorded thermal images allowed calculating several thermal parameters, such as thermal time constants of particular brake elements (1), (2). Those data were used to verify the numerical model of the brake. They also can be the guidelines to optimise the brake design with respect to heat transfer aspects.