Reliability optimization design method of automobile engine connecting rod bolt

Reliability Optimization Design Method of Automobile Engine Connecting Rod Bolts Si Chuansheng, Department of Transportation, Huaiyin Institute of Technology, Jiangsu Huai'an 223001, optimized design model to combine the two.

1 Introduction The connecting rod bolt is a critical fastener that requires sufficient fatigue strength and anti-loosening properties. There must be strict requirements in design, manufacturing, and quality management. There are usually many methods used in bolt design. Such as the optimization design method finite element method reliability design method value engineering method, etc., no matter which method is adopted. It is natural for people to choose a solution that is better at achieving a predetermined goal. It can ensure the safe and reliable operation. This paper intends to combine the reliability design and optimization design method of connecting rod bolts, that is, while achieving the reliability goal, it should also adopt the optimization method to reduce the cost and improve its working performance and carrying capacity. .

The basic idea of ​​reliability optimization design of connecting rod bolts is to require bolts to meet the performance requirements. Maximize reliability or maximize structural or component performance. It is required that the reliability of its work is not lower than a certain level. Using the mathematical model for maxRXs.tfXGo or generation, only the function of the part's predetermined reliability, part cost function or other performance parameters 2 to establish a probabilistic optimization design model. Because reliability design is a probabilistic design, it is obvious in the optimization design. In this case, the design point is required to be satisfied by a certain probability level; the constrained random function; the stochastic random design variable; the degree ultimate hardness elastic modulus. Or part reliability parameter strength stiffness stability, etc.

The inequality constraint of the above formula is called a probability constraint.

In the optimization design question, when the design variables and parameters in the design model are random, and the constraints contain the probability constraints, the model is called the probability optimization design model. The most representative and most commonly used probability model is the mean model. The form is miiiEfx.w called the whole of the event, called the probability of the event; 0 is the deterministic variable, that is, the random variable with the standard deviation of zero.

The design point when finding the minimum value in the probability feasible domain is the optimal solution of the probability optimization design.

3 model solving method The basic idea of ​​the solution method of this particular mean model is to transform the probability model into a deterministic model, and then solve the mean of the random variables according to the deterministic optimization method, and set the probability constraint, and both are normal. The distribution, and independent of each other, the random constraint function 8 can also be normally distributed.

Let 2=8 be known by probability theory. The probability density function of 2 is also a normal distribution, and its mean value, =1 standard deviation = 20, is the probability that the probability constraint is guaranteed.

In order to transform the above equation into a standard normal distribution. Let the standard state variable 12 = 1 can be transformed into a symmetric distribution due to the normal distribution. Therefore, the above formula is transformed into a gray order 9, then. 1 The sinusoidal function design requirement is 870. The same reason can be obtained. Equation 1 and 2 are random constraints. The equivalent value is converted to the deterministic constraint. The mean and the standard are the average of a random Qin. The standard deviation of random factors.

The reliability optimization design of the 4-link bolt optimizes the design model according to the above probabilities. We can design the connecting rod bolts.

4.I design requirements are required to be based on the principle of lightest importance. Under the condition of ensuring reliability. The bolt size and number are preferred.

The maximum pressure at which the conditions are known to work, the diameter of the large hole of the connecting rod, the material of the bolt and the member to be coupled. structure. Load effect. Assume that the design variables and parameters of the positional gasket material obey the normal distribution 4.2 and establish a mathematical model. 4.2.1 Establish the objective function. Set the total weight of the bolts to 3. Bell 1d bolt nominal diameter 1di screw inspection diameter 0 bolt material weight 1. For steel bolts 1. Spiral equivalent long cast design variable, = 1.121 = 2, mountain 1 4.2.2 bolt static strength conditions. , 霰 总 total pull force 1 heart + work tension bolt residual pre-tightening force F = 1.5F statistic of the maximum tensile stress in the bolt is the small limit of the yield limit of the bolting of the bolt of the formula 1 (3) 4. 2.3 Fatigue strength condition of connecting rod bolts flashes the tension of the bolts in the tension 1 total tension 1.

Therefore, the average value of the bolt force should be Sa=2KeT5K; the type of gasket used in iPVZd. It is assumed that the bolt stress is normally distributed. Then you can treat it with reliability! 1 to the constraint condition is snail, pill 崭, ∽ chicken gt; 5 4.2.4 bolt connection tightness limit In order to ensure a reliable tightness between the connecting rod cover and the connecting rod body, the distance between the bolts is required to meet Therefore, the conclusion can be passed through the above analysis. We are designing the connecting rod bolts. As long as the reliability requirements are guaranteed above. It also guarantees the best performance or parameters and ultimately meets the design goals. Similarly, in the design of bolts for other purposes, you can also refer to this design idea, 1 Ouyang Zuxing, Yin Mingde. Mechanical reliability design. Nanjing University of Aeronautics and Astronautics, Nanjing, 1994.

3 Liu Shanwei. Reliability optimization design of mechanical parts. Beijing China Science and Technology. Generation publishing house. 1 4 Gong; 1 cold. The steam generation is designed and manufactured. Jingren Traffic Publishing 5th. Modern design of automobile engine 1 Beijing People's Traffic Publishing, so 1 continuous and bounded, according to everyone 8, out the theorem, in the Ding mapping, the image is tight, applying the mountain 1 fixed point theorem, there is another lemma 3 That is, the conclusion of the theorem.

Original, hateful, Ma Zhien. Global Existence of Periodic Solution for a Predator-Prey System 1. Xi'an Jiaotong University, 2000.341080, 83.

Then 0 is a closed convex subset in .

Cobalt metal is mainly used for making alloy. Cobalt-based alloy is cobalt and chromium, tungsten, iron, nickel group made of one or more of the general term. Tool steel containing a certain amount of cobalt can significantly improve the wear resistance and cutting performance of steel. Stellite hardeners containing more than 50% cobalt do not lose their original hardness even when heated to 1000 ° C. Nowadays, these cemented carbides have become the most important material for use between gold cutting tools and aluminum. In this material, cobalt alloyed with other metal carbide grains together to make the alloy with higher toughness and reduce the sensitivity to impact, the alloy welding on the surface of the parts, the parts can make Life expectancy increased by 3-7 times.