The research that oscillatory effectiveness for a given period of time affects to intensity of metallic structure exhaustion

57 　 oscillatory effectiveness for a given period of time is in recent years a kind of arisen advanced technique, because this kind of technology has a lot of advantage, course of study of our country machining begins generally already to use, and already was more and more people place accept. It is OK already that technology of oscillatory effectiveness for a given period of time is reducing leftover stress respect rival with heat treatment photograph, but the influence problem of fatigue to metallic structure life, have bigger difference opinion, we undertook study to this. 1 leftover stress serves as pair of material to bear to the influence of fatigue life dynamic the influence of function, leftover stress is important to the influence of the fatigue intensity of material. From qualitative angle, concern commonly and talk, should be handed in change when the component part existence of stress reduces leftover stress, the fatigue intensity of this component can rise, and when stress of existence drawing remains, its exhaustion intensity can drop. Actually, because of condition and environment different, leftover stress is complex to fatigue influence. Of it and leftover stress distributing and the condition of stress of the stretch function of size, material, foreign action about, still with the happening of leftover stress the process is concerned. Because solder, cast, the leftover stress that the craft such as cold working causes abounds in in engineering construction, about leftover stress the influence of fatigue to the structure intensity already began to cause the attention of people. From much experimentation the result can see, the influence of leftover stress nots allow to ignore. Graph 1, graph 2 it is to part to provide node and the test result that bring transverse butt welding to seam test specimen to soldering. Test result explains, of fatigue life rising is the result that eliminates stress. Because, here used technology of oscillatory effectiveness for a given period of time to eliminate the leftover stress in test specimen above all, and this kind of technology won't produce metallurgy effect in test specimen. Accordingly, can confirm the leftover stress distinct effect to fatigue intensity adequately. Graph exhaustion of 1 canal node experiments to pursue as a result this kind of influence of stress of remains of result of test of exhaustion of small test specimen of 2 leftover stress is OK from rupture get explanatory in mechanical theory. In much experimentation people discovers, besides K of △ of amplitude of stress intensity factor, the element such as average stress is right of fatigue crackle patulous influential also, this kind of influence is OK from the graph 3 be pleasant to the eye piece. Gave out to be in in the graph different loop feature (R=Kmin/Kmax) when, with the Da/dN- that formula of P α Ris arranges? K curve. Be in same? When K, r value is greater (namely average stress is taller) , da/dN is bigger. Accordingly, average stress is press stress, fatigue crackle expands rate will is than average stress when pulling stress low, this watch palpability compresses remains to answer R=0.

103 force can increase fatigue strength. Graph 3 average stress are patulous to crackle the influence of rate 2 oscillatory effectiveness for a given period of time and technology of effectiveness for a given period of time of fatigue life vibration reduce leftover stress effectively, stabilize structural dimension, already was proved by much experimentation, from this action for, oscillatory effectiveness for a given period of time also will increase fatigue strength of the structure. Plant of some railroad car produces structural frame of bogie of cast steel passenger car formerly, structural frame solders because of needing instead after. Because output is big, make hot ageing treatment, time has not enough time, and need to build kiln of fire of large boil in a covered pot over a slow fire to expend a large number of the sources of energy. Instead vibration ageing treatment, solved afore-mentioned problems, improved the fatigue life of structural frame. Passenger car bogie solders structural frame basically bears in move exhaustion carries a plan 3 average stress expand to crackle the influence of rate carries on his shoulder or back. Fatigue fracture is the main type that its invalidation destroys. Solder each transverse weld is reached on structural frame solder the stress such as contact centers an area, it is the main area that generates fatigue source. Divide outside undertaking burnish processing be centered in order to eliminate stress to these dots, oscillatory processing basically depends on removing the leftover stress effect to fatigue life. Handle technology to make this vibration, with solder bridge of structural frame side (basically bear the weight of bridge) the comparative test that does fatigue life, among them one did not do any processing; One makes normal hot ageing treatment; Another is pressed " 1/2 load law " make oscillatory ageing treatment. The comparative sex that makes fatigue life below identical imitate load again next experiments. By the experiment of subordinate list the result can be seen, oscillatory effectiveness for a given period of time is used to be able to improve its exhaustion life significantly on side bridge, and the effect of specific heat effectiveness for a given period of time is good. And technology of oscillatory effectiveness for a given period of time goes easily simply, apply in production, can obtain remarkable economic benefits. Solder life of craze of type of effectiveness for a given period of time of number of table of data of test of exhaustion of bridge of structural frame side raises rate gross life lead effect of 1 the period of the day from 1 p.m. to 3 p.m. 143100 　 2 heat of 456000 　 effectiveness for a given period of time 158000 than 1 tall 10.

4%491500 is compared 1 tall 7.

8%3 oscillatory effectiveness for a given period of time 362000 than 1 tall 152.

9%934300 is compared 1 tall 104.

9% 　 do not pass, oscillatory load also is a kind of fatigue load, accordingly, process of oscillatory effectiveness for a given period of time also can say is " fatigue " process, it whether cause fatigue loss, the problem that reduces fatigue intensity is people to pay close attention to all the time. Be opposite to consider oscillatory effectiveness for a given period of time the influence of fatigue life, we did two groups not to have leftover stress the fatigue life test of smooth small test specimen, test specimen offers goods condition and the test specimen that handle via vibration for material. Its see a picture as a result 4, from the graph 4 in the test specimen that can see classics vibration ageing treatment and not 7.

57.

06.

Its exhaustion intensity does not have the test specimen of ageing treatment of 5 classics vibration apparent difference. Apparent and oscillatory effectiveness for a given period of time did not cause fatigue loss, yi Mo reduces fatigue intensity. Graph 4 without leftover stress exhaustion of small test specimen experiments result 3 summary the article passes contrast of a few fatigue life to experiment, sufficient proof: Leftover stress is serious to the influence of life of metallic structure exhaustion, the key of oscillatory effectiveness for a given period of time depends on eliminating or reduce the leftover stress of metallic structure. The technology of oscillatory effectiveness for a given period of time that because this serves as,is main purpose in order to eliminate leftover stress can improve the fatigue life of metallic structure. CNC Milling