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 Wysłany: Pią 16:09, 17 Gru 2010 Temat postu: ed hardy clothing Level of an engine turbine blade |
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Level of an engine turbine blade fracture analysis
When one of the load can not afford a place leaves broken fragments of other leaves will be injured, the accident will be formed above the engine. 3.2 In summary and development of cracks, the crack initiation and propagation process is as follows: (1) In a particular engine is running, causing the turbine gas flow field flutter ring true, too much resonance with centrifugal stress stress and aerodynamic,[link widoczny dla zalogowanych], so that defects or loose the blade at the initiation of micro cracks, and in the normal alternating loads began to expand, as shown in Figure 5,[link widoczny dla zalogowanych], the crack initiation area of the small plane smooth,[link widoczny dla zalogowanych], oxidation serious, there are clear micro-cracks and holes. The small plane is in the normal cyclic loading, crack growth rate is very slow, and the repeated opening and closing of cracks, the friction between the two sections formed. A longer time due to the formation,[link widoczny dla zalogowanych], oxidation section is very serious. (2) the formation of a small plane crack propagation, due to reduced cross-section blade and effective force, the crack started in alternating load faster expansion into the stable expansion of the first stage, shown in Figure 3, the class cleavage fracture morphology and Figure 4 morphology of the slip steps. Crack propagation time, into the stable expansion of second phase, shown in Figure 5 and Figure 6, the section has the typical fatigue striation. Figure 2 A, morphology is the formation of these two stages, the district oxidation serious, consistent with high-cycle fatigue fracture surface fracture morphology, and thus concluded that the formation of high-cycle fatigue is the cause of this crack [2]. (3) The blade cracks, and its natural frequency changes. When the engine test and run to the last transition speed 8000r/min, the blade natural frequency and engine excitation frequency close or coincide, causing the larger leaves of the resonance, leaves the remaining section of the load is too large can not afford to start rapid expansion (Figure B-2 District, the area A, is significantly more oxidized light). When the leaves of a fault, they formed the accident. 4 Conclusion (1) turbine blade failure modes for mechanical fatigue failure. (T turn p. 215) amide ∞ ∞ aluminum commonly used measurement uncertainty reported that in two ways. RL on the lower yield strength as a: ① R a 380N/mm, U a 23N/mm, Chih-yi 2; ② RL A (380 ± 23) N / mm; Chi-2. I use ①, so in this case under the study tensile yield strength R R, Elongation Measurement Uncertainty reported as follows: ReL a 380N/mm, U a 23N/ramz, k a 2; R a 565N/mm, U a 34N/mm, k A 2; A a 21.5, U a 0.8%, chi-2. The meaning is: You can expect 380_-Z-23N/mm range includes the lower yield strength may be measured values of ReL 95; in the range 565 ± 34N/mm contains possible values of tensile strength measurements R 95; In 21.5 ± o. 8 interval contains the results of the Elongation A measurement of the 95 possible values. (Continued from page 204) (2) leaves the direct external cause of cracks is caused by too much chatter resonance stress within the inner leaf due to metallurgical defects, the two leaves under the action led to crack initiation. (3) by controlling the blade natural frequency, the transition speed to avoid resonance, and control the metallurgical quality of the leaf, thermal processing parameters and surface quality to improve the fatigue resistance of the leaves. 3 Discussion (1) the factors that affect the tensile test results of well test rate, sampling location, sample processing, material uniformity, the sample holding method, coaxial and so force, if necessary, and the conditions allow these factors uncertainty components arising should also be assessed. If some factors, such as the sampling site is in strict accordance with GB/T2975--1998 standards, sample processing has been in strict accordance with the relevant standards and meet requirements, then the sample site and sample processing can be caused by the negligible uncertainty . Rate of the pilot see [6] The Fifth Lecture of Table 5-4. (2) in the mechanical test, the total need some measuring on the sample size and the fracture scale to measure distance by measuring the maximum allowed the indication error of measurement uncertainty can be introduced by direct reference to the literature [6] the first Five speakers presented the data in Table 5-3. (Continued) References: [1] Wang Changyuan, Long Lin. Turbojet engine turbine blades of a failure analysis of IJ]. Reliability, 1997, (1) :9-14. [2] Tao Chunhu. Fracture Rotator component failure analysis [M]. Beijing: National Defence Industry Press, 2000. [3] Lau new. Fracture Analysis of three engine turbine blades [J]. TESTING A physical volumes, 1998,34 (12) :33-35. * 215 *
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