Creating a Creep Curve
Posted: Sat Dec 28, 2024 6:52 am
. Applying a Fixed Load
The test first uses a constant load on a test sample of the material or stress as a percentage of the material's yield strength. The technician applies the load precisely to exert a similar pressure throughout the sample. This load represents actual load conditions the material may experience, including bearing a static load or overcoming a steady load.
2. Monitoring Strain Over Time
After applying the load, technicians monitor the material's ability to change shape frequently over a specified time. This monitoring can take place from hours through days to several weeks. Technicians use strain gauges during the test to monitor changes as slight as those in the material's shape.
They maintain the temperature to be constant during the test since heat affects the flow of Creep in the test environment. This phase involves regularly measuring the material's deformation over time to capture the changes across the three stages of Creep.
The technicians collect and present the data as a vertical time and strain axes graph. The resulting creep curve clearly illustrates the creep behavior of the material under constant stress. Engineers can deduce various properties from this curve, including creep rate during the second stage and time to failure in the third stage. By understanding this behavior, engineers and researchers can determine if the material will meet expectations in the long term and follows certain applications, such as construction, aerospace, or automotive.
Real-World Examples of Creep
The most familiar case of Creep is identifiable in plastic loan database pipes. They result from plastics in pipes carrying water in plumbs and irrigation channels. These pipes experience internal water pressure, which is steady, so there is a continuous load on the material. Eventually, it puts pressure on the pipes, and they can either hang or change their shape in areas where they elongate without reinforcement. High temperatures, for example, in heater systems, push the pipes to the point of elongation or failure much quicker than at average home temperatures.
Understanding the concept of Creep helps engineers to choose the right materials, such as cross-linked polyethylene (PEX).
Creep also affects automotive parts, particularly those susceptible to high heat and stress. For example, the dashboard panels and inner trims from ABS (Acrylonitrile Butadiene Styrene) look faded and lose their initial shape within a few years. These components experience mechanical stress and exposure to heat from sunlight, which looks unpleasant and interferes with operations. Automotive designers alleviate this by using heat-resistant materials, re-enforcement, or ways to modify the stress concentrations.
Creep is a complicated factor in medical devices since safety and reliability are critical. For instance, prosthetic devices must employ lightweight polymeric materials for the lightweight structure. These materials must keep their structure and performance stable after years of use. Cyclic loading caused by the patient's weight and the movements can cause the load to become gradually deformed if the material does not have high creep resistance. To manage this risk, manufacturers employ high-performance polymers such as polyetheretherketone (PEEK) to manufacture the devices. They also incorporate composites into the designs of the devices to make them more enduring and functional for a more extended period.
The test first uses a constant load on a test sample of the material or stress as a percentage of the material's yield strength. The technician applies the load precisely to exert a similar pressure throughout the sample. This load represents actual load conditions the material may experience, including bearing a static load or overcoming a steady load.
2. Monitoring Strain Over Time
After applying the load, technicians monitor the material's ability to change shape frequently over a specified time. This monitoring can take place from hours through days to several weeks. Technicians use strain gauges during the test to monitor changes as slight as those in the material's shape.
They maintain the temperature to be constant during the test since heat affects the flow of Creep in the test environment. This phase involves regularly measuring the material's deformation over time to capture the changes across the three stages of Creep.
The technicians collect and present the data as a vertical time and strain axes graph. The resulting creep curve clearly illustrates the creep behavior of the material under constant stress. Engineers can deduce various properties from this curve, including creep rate during the second stage and time to failure in the third stage. By understanding this behavior, engineers and researchers can determine if the material will meet expectations in the long term and follows certain applications, such as construction, aerospace, or automotive.
Real-World Examples of Creep
The most familiar case of Creep is identifiable in plastic loan database pipes. They result from plastics in pipes carrying water in plumbs and irrigation channels. These pipes experience internal water pressure, which is steady, so there is a continuous load on the material. Eventually, it puts pressure on the pipes, and they can either hang or change their shape in areas where they elongate without reinforcement. High temperatures, for example, in heater systems, push the pipes to the point of elongation or failure much quicker than at average home temperatures.
Understanding the concept of Creep helps engineers to choose the right materials, such as cross-linked polyethylene (PEX).
Creep also affects automotive parts, particularly those susceptible to high heat and stress. For example, the dashboard panels and inner trims from ABS (Acrylonitrile Butadiene Styrene) look faded and lose their initial shape within a few years. These components experience mechanical stress and exposure to heat from sunlight, which looks unpleasant and interferes with operations. Automotive designers alleviate this by using heat-resistant materials, re-enforcement, or ways to modify the stress concentrations.
Creep is a complicated factor in medical devices since safety and reliability are critical. For instance, prosthetic devices must employ lightweight polymeric materials for the lightweight structure. These materials must keep their structure and performance stable after years of use. Cyclic loading caused by the patient's weight and the movements can cause the load to become gradually deformed if the material does not have high creep resistance. To manage this risk, manufacturers employ high-performance polymers such as polyetheretherketone (PEEK) to manufacture the devices. They also incorporate composites into the designs of the devices to make them more enduring and functional for a more extended period.