| Three-dimensional stress fields of the impact test sample with standard notch were studied, the stress status in the middle plane and the stress concentration factor were analyzed, and the process of impact was dynamically displayed in this article by means of the ANSYS finite element analysis software. By changing the formal dimension of impact test sample, the variety of the stress status in the middle plane and the primary factors were analyzed. The process of deformation and rupture for forging Al-alloy LD2 were particularly enregistered through impact testing machine with oscillometer, and the stress status of impact test sample with Charpy V notch was analyzed by ANSYS finite element analysis software in this article. Based on the investigation of dynamic linear-elastic fracture, dynamic analyses method of crack initiation and propagation for typically ductile and brittle materials under impact loading was suggested through instrumented impact testing machine. Based on the method in which specimens were exposed to hydrogen environment, The impact property testing of ZL114A alloy containing various contents of hydrogen, and its microstructure and fracture analysis were made to study the hydrogen sensitivityof impact test sample with different notch and fracture mechanism. The macroscopical fracture and distortion, the microstructure, and the scanning electron microcopy photographs of microcosmic fracture of impact test sample were observed by means of changing heat treatment for found Al-alloy HZL201 for aviation. Through testing generally mechanical properties of HZL201 alloy at room temperature, the process of deformation and rupture for Al-alloy HZL201 were particularly analyzed. By means of the comparison of all the test result, the rupture mechanism of Al-alloy were studied, the new method for the toughness appraisement of test material was brought forward from the article. The heat treatment means have been selected in the article can improve generally mechanical properties of HZL201 alloy and direct practice production. The results indicated that,(1) The stress status in the middle plane of the impact test sample with standard notch was analogical and the maximally equivalent Von Mises stress (SEQV) appeared at notch root, the stress concentration factor of standard notch Kt was the function of time, and the time responding to rupture at notch root varied with notch type.(2) The stress distributing of impact test sample was distinct owing to formal dimension at the notch and the curvature of notch influenced mostly the stress concentration of the impact sample to a great degree.(3) The impact test sample with I notch was designed according to the above results in order to strengthen the material stress status and greatly enhancesensitivity of high toughness material by means of impact test.(4) Though fracture will occur when crack propagation energy is much higher than initial energy and vice versa. Forging Al-Alloy LD2 for aviation was a high ductility aluminum alloy because that the total energy of plastic deformation and crack propagation were bigger than its elastic deformation energy, the limitation of impact test application was pointed out in material diagnosis.(5) The obvious difference occurred at impact toughness of different samples with variational hydrogen contents, the hydrogen sensitivity of impact test sample with ZI notch was better than others, and the impact test sample with NT notch was practicality while the hydrogen content was about O.lml/lOOg(6) With the increase of the ,hydrogen content in the alloy, impact toughness increases at different speed; the impact toughness was affect by the form and distributing of hydrogen.(7) In this research, with the increase of the aging time for Al-alloy HZL201, impact work and impact load decreased at different speed, and the trend was the same as the results of the elongate test and opposed to the rigidity test. The found Al-alloy HZL201 for aviation in T4 heat treatment was provided with preferable generally mechanical properties at room...
|
PDF Full Text Request