What are the fatigue endurance tests?
A vehicle or component company, in order to validate its products, conducts a variety of tests, of whichFatigue endurance testIt is the most important type of test because it directly verifies the product's life or life and failure rate.
One of the first concepts mentioned before this isReliability testReliability test and fatigue test are fundamentally different, reliability test is a vehicle based on the time domain of the test, is to verify that the product in the specified time to show the design of the normal functionality of the possibility of belonging to the consideration of product quality level with the significance of time change. And fatigue test is for the product life requirements to verify, is a kind of accelerated test, usually in the laboratory. But there are also some companies test personnel will use the reliability test to express the meaning of fatigue test, as long as we are clear about the meaning can be.
Fatigue test compared to the actual user to drive the car, then it can be understood as equivalent to a driving a very violent user, the road conditions are extremely harsh harsh, so as to verify the user in a short period of time for a long time to use the situation, but also limited to this understanding, because if the reality is really driving the car like this, theoretically may instantly lead to automobile break down, the meaning of the fatigue test is expressed here It is a kind of accelerated test, and it is very important to deeply understand the correlation between the fatigue test in the laboratory and the user's use.
There are mainly many kinds of classifications for fatigue test, and CIIC is divided into two major categories according to its own understanding for basic introduction.
1 Structural fatigue test
Mainly for structural components for fatigue testing, where the structural components in accordance with the size of the structural components at the system level, there are simple components level structural components; in accordance with the form of load-bearing structural components, there are non-load-bearing structural components; the author's perennial work is also a gradual and profound feeling that the simpler the structural components, fatigue test design is also more difficult.
1.1 Structural elements for load bearing
For loaded structural components, loading verification of the test specimen is usually done in a test laboratory by means of an actuator with appropriate test fixtures according to the actual form of force used.
The main loading methods are conventional constant amplitude loading, where the actuator is operated at a certain frequency for a long period of time in a sinusoidal manner, but of course the length of the operation depends on the design life of the product.
There are also structural components loaded in accordance with the program block test, as for the program block in what order how to define the size of the block spectrum needs to be tested with a deep fatigue theory to effectively design out the test results for many types of structural components than the fixed-amplitude loading good.
There is also a recent emerging simulation of the time domain data for loading, which requires the laboratory should also have the corresponding hardware and software investment, this verification method is almost the same as the user's actual use, but also the most accurate one, but the realization is also very troublesome, the requirements of the test personnel to pull up.
1.2 Unloaded structural elements
For non-load-bearing structural components, here the non-load-bearing mainly refers to some accessories or mounted on the frame of the structural components of the system, such as trucks on the cab, usually do not bear the huge load brought about by the operation of the vehicle, the main bear vibration, the vibration experienced by a long time to a certain extent, the structural components will also appear failure.
Here there are two common forms of loading, but the corresponding need for the laboratory with the corresponding hardware and software investment, one is based on the time domain vibration signal of the road simulation loading, the structural components in the laboratory vibration and the user's actual driving under the structural components of the vibration is the same; there is another based on the frequency domain loading vibration durability, the structural components of the vibration of the laboratory in the measured data and the user's actual driving under the structural components of the vibration signal is not the same, only the root mean square value curve is somewhat related, but the validation effect is very good. There is another vibration durability based on frequency domain loading, the measured data of the vibration of the structural member in the test chamber and the vibration signal of the structural member under the actual driving of the user are not the same, only the root mean square value curve has a certain connection, which is very abstract, but the verification effect is very good.
2 Transmission Fatigue Test
Transmission system mainly refers to the vehicle transmission, driveshaft and drive axle, the fatigue endurance test of the transmission system is more important, directly related to the image of the core products in the minds of users.
2.1 Transmission fatigue test
Transmission fatigue test, mainly in the test chamber through the drive unit drive transmission input, there are corresponding load unit to provide load, of course, this process is not only to verify the gears, but also to verify the clutch bearings and other very important transmission parts, the specific form of loading there are constant torque loading and variable torque loading, specific how to load the test personnel require a deep understanding of the structure of the product operating characteristics and applications. The specific how to load requires the tester to deeply understand the product structure, operating characteristics and applications.
2.2 Driving axle fatigue test
Drive axle fatigue test, if in the test chamber through the drive unit drive gearbox input, there are corresponding load unit to provide load, of course, this process is not only to verify the gears, but also verify the bearings and other very important transmission parts, the specific form of loading there are fixed torque loading and the program block torque loading, specific how to load is also required to test the staff to deeply understand the structure of the product work characteristics and applications.
2.3 Drive shaft fatigue test
Transmission shaft fatigue test, here does not refer to the fatigue test of the shaft body, because that belongs to the category of structural fatigue test, this title refers to the fatigue test of the bearing components in the transmission shaft, the main form of loading fixed torque loading and program block torque loading, the specific how to load the requirements of the testers a deep understanding of the product's structural operating characteristics and applications.
2.4 Bearing fatigue test
Bearing fatigue test, do this kind of test need test personnel with conventional bearing knowledge, can be read in detail through the mechanical design of the bearing part to understand, because the more simple parts more difficult to design the test can be reflected here, the design of the bearing fatigue test room a very difficult job, the definition of the load and speed of the test bench are built on a deep background knowledge.
2.5 Engine Fatigue Test
Engine fatigue test, general engine products fatigue test engine suppliers are better at some, not described here.
To summarize, there are all kinds of fatigue tests in the laboratory, and it requires that the testers do have a strong interest and a deep fatigue theory in order to really do a good job of fatigue testing, and it is very important that fatigue testing is not in accordance with certain standards to operate the equipment; however, for the national standards used in the test, just read them, and those who write the standards do not know how your product works.