The selection of the membership function bolt material for material selection and determination of the yield limit can be determined empirically or by analogy. According to GB309811) 82 for the performance level of the fastener, the ultimate strength of the material can be determined after the selected performance level. Here, the lower limit Rsmin of the yield limit of the bolt material is defined as the strength limit of the bolt material. Knowing the maximum working load mean value Q6 and the number of bolts n of the bolt set, the maximum working load average value of each bolt is Qp=Q6/n, and the mean value of the stress caused by the working load of each bolt is Rp=4QPPd2(4) d is the thread diameter, mm. The known working load variation coefficient <2>VQ=$Qp3Qp, then the standard deviation DRp=VQRp(5) sets the pre-tightening stress of each bolt due to the pre-tightening force to Ri, according to the literature. <2>, the pre-tightening stress coefficient of variation VR is generally taken as 01149, then its standard deviation DRi=01149Ri(6) According to the literature <1>, the total tensile force Q of the axially loaded tight bolt is Q=C1C1+C2Qp+ In the Qi type: Qp is the bolt working load; Qi is the pre-tightening force; C1, C2 are the stiffness of the coupling member and the connected member respectively, and the ratio C=C2/C1, then the total value of the Q=11+CQp+Qi bolt The working stress mean is R=11+C@Rp+Ri(7) and finally determines the membership function of the bolted joint. According to the fuzzy reliability design criterion, under the action of variable load, the normal working state and the failure state of the pre-tightening bolt are not completely separated, but a gradual transition process. According to the characteristics of the fuzzy variable of material strength, using the fuzzy statistical method, we select/subtract the semi-ladder distribution 0 function to express the membership function of the yield limit of the material: uA(x)=1x grinder. Vibration angular frequency X=10216s-1, vibration amplitude A=8mm, grinding tube quality (including medium) m=4500kg, using 12 M24 high-strength bolts (grade 1019) to be connected with frame, pressure code and grinding tube. Try to find the fuzzy reliability of the bolt group connection R. For the 1019 high-strength bolt, the nominal tensile strength Rb=10001200MPa, according to the load characteristics of the vibrating mill pressure-coded bolt and the reliability of its connection, the bolt should adopt the critical plastic zone pre-tightening method <4>, which It is also allowed for high-strength bolts. At this time, the pre-stressing stress average value is Ri=017. Conclusion Through the fuzzy reliability design of the vibrating mill's coded bolt connection, we have a basis for reliability in determining the preload. It can be seen that when the preload stress is selected at 017
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