Mechanical stress is a significant factor that can contribute to component failure in various industries. As a component failure analysis supplier, we have witnessed firsthand the detrimental effects of mechanical stress on different types of components. In this blog, we will explore how mechanical stress contributes to component failure and discuss some of the key mechanisms involved.
Understanding Mechanical Stress
Mechanical stress refers to the internal resistance of a material to an external force or load. It can be caused by a variety of factors, including vibrations, shocks, thermal cycling, and improper handling or installation. When a component is subjected to mechanical stress, it experiences deformation, which can lead to structural damage and ultimately failure.
There are several types of mechanical stress, including tensile stress, compressive stress, shear stress, and torsional stress. Tensile stress occurs when a material is pulled apart, while compressive stress occurs when a material is squeezed together. Shear stress occurs when a material is subjected to forces that cause it to slide or deform in a parallel direction, and torsional stress occurs when a material is twisted.
Mechanisms of Component Failure Due to Mechanical Stress
Fatigue Failure
One of the most common mechanisms of component failure due to mechanical stress is fatigue failure. Fatigue failure occurs when a component is subjected to repeated or cyclic loading, causing microscopic cracks to form and grow over time. These cracks can eventually lead to catastrophic failure of the component.
Fatigue failure is often associated with components that are subjected to vibrations or cyclic loading, such as engine parts, aircraft components, and automotive components. For example, in an engine, the pistons, connecting rods, and crankshaft are all subjected to cyclic loading, which can cause fatigue failure over time.
Creep Failure
Creep failure is another mechanism of component failure due to mechanical stress. Creep failure occurs when a component is subjected to a constant load over an extended period of time, causing it to deform slowly and eventually fail. Creep failure is often associated with components that are subjected to high temperatures and high stresses, such as turbine blades, boiler tubes, and nuclear reactor components.
For example, in a gas turbine engine, the turbine blades are subjected to high temperatures and high stresses, which can cause creep failure over time. As the blades deform, they can lose their aerodynamic shape, leading to reduced efficiency and increased fuel consumption.
Brittle Fracture
Brittle fracture is a sudden and catastrophic failure that occurs when a component is subjected to a high stress without significant plastic deformation. Brittle fracture is often associated with components that are made of brittle materials, such as ceramics, glass, and some metals.
Brittle fracture can be caused by a variety of factors, including manufacturing defects, improper heat treatment, and environmental factors. For example, in a ceramic component, a small crack or flaw can act as a stress concentrator, causing the component to fail under a relatively low stress.
Corrosion Fatigue
Corrosion fatigue is a combination of corrosion and fatigue that can cause component failure in environments where corrosion is present. Corrosion fatigue occurs when a component is subjected to cyclic loading in a corrosive environment, causing the corrosion to accelerate and the fatigue cracks to grow more rapidly.
Corrosion fatigue is often associated with components that are exposed to seawater, chemicals, or other corrosive substances, such as offshore oil and gas platforms, chemical processing equipment, and marine vessels. For example, in an offshore oil and gas platform, the steel pipes and structures are exposed to seawater, which can cause corrosion fatigue over time.
Case Studies
To illustrate the impact of mechanical stress on component failure, let's look at some real-world case studies.
Case Study 1: IGBT and Semiconductor Testing
Insulated Gate Bipolar Transistors (IGBTs) and semiconductors are critical components in many electronic devices, such as power supplies, motor drives, and renewable energy systems. These components are often subjected to high temperatures, high currents, and mechanical stress, which can cause them to fail prematurely.
In one case, a customer came to us with a problem of IGBT failures in their power supply system. After conducting a thorough failure analysis, we found that the IGBTs were failing due to thermal cycling and mechanical stress. The thermal cycling caused the solder joints to crack, and the mechanical stress caused the bonding wires to break.
To solve the problem, we recommended a series of design changes, including improving the thermal management of the power supply system, using a more robust solder material, and increasing the bond strength of the bonding wires. We also provided the customer with IGBT and Semiconductor Testing services to ensure the reliability of their IGBTs and semiconductors.
Case Study 2: Power Module Aging and Test Verification
Power modules are widely used in power electronics applications, such as electric vehicles, industrial drives, and renewable energy systems. These modules are often subjected to high temperatures, high currents, and mechanical stress, which can cause them to age and degrade over time.
In another case, a customer came to us with a problem of power module failures in their electric vehicle. After conducting a detailed failure analysis, we found that the power modules were failing due to thermal aging and mechanical stress. The thermal aging caused the die attach material to degrade, and the mechanical stress caused the ceramic substrate to crack.
To address the issue, we recommended a series of aging and test verification procedures, including accelerated life testing, thermal cycling testing, and vibration testing. We also provided the customer with Power Module Aging and Test Verification services to ensure the long-term reliability of their power modules.
Case Study 3: PCB Board-Level Process Quality Evaluation
Printed Circuit Boards (PCBs) are the backbone of many electronic devices, providing electrical connections between components and mechanical support for the entire system. However, PCBs are often subjected to mechanical stress during the manufacturing process, such as drilling, routing, and soldering, which can cause them to fail.
In a third case, a customer came to us with a problem of PCB failures in their consumer electronics product. After conducting a comprehensive failure analysis, we found that the PCBs were failing due to poor board-level process quality. The drilling and routing processes were causing microcracks in the PCB substrate, and the soldering process was causing voids and cold joints.
To improve the board-level process quality, we recommended a series of process optimization measures, including using a more precise drilling and routing machine, improving the soldering process parameters, and implementing a rigorous quality control system. We also provided the customer with PCB Board-Level Process Quality Evaluation services to ensure the reliability of their PCBs.
Preventing Component Failure Due to Mechanical Stress
To prevent component failure due to mechanical stress, it is important to take a proactive approach to design, manufacturing, and testing. Here are some key strategies that can help:
- Design Optimization: During the design phase, it is important to consider the potential sources of mechanical stress and design the component to withstand these stresses. This may involve using stronger materials, optimizing the shape and size of the component, and providing adequate support and reinforcement.
- Manufacturing Process Control: During the manufacturing process, it is important to control the variables that can affect the mechanical properties of the component, such as temperature, pressure, and machining parameters. This may involve using advanced manufacturing techniques, such as precision machining and additive manufacturing, and implementing a rigorous quality control system.
- Testing and Validation: Before the component is put into service, it is important to test and validate its performance under realistic operating conditions. This may involve conducting mechanical testing, such as tensile testing, compressive testing, and fatigue testing, and using simulation tools to predict the behavior of the component under different loading conditions.
- Monitoring and Maintenance: Once the component is in service, it is important to monitor its performance and condition regularly to detect any signs of damage or degradation. This may involve using sensors and monitoring systems to measure the mechanical properties of the component, such as stress, strain, and vibration, and implementing a preventive maintenance program to replace the component before it fails.
Conclusion
Mechanical stress is a significant factor that can contribute to component failure in various industries. By understanding the mechanisms of component failure due to mechanical stress and taking a proactive approach to design, manufacturing, and testing, it is possible to prevent component failure and ensure the reliability and safety of critical systems.
As a component failure analysis supplier, we have the expertise and experience to help you identify the root cause of component failure and develop effective solutions to prevent future failures. If you are experiencing problems with component failure or would like to learn more about our services, please contact us to discuss your specific needs. We look forward to working with you to ensure the reliability and performance of your components.
References
- ASM Handbook, Volume 11: Failure Analysis and Prevention, ASM International, 2002.
- Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue, Donald R. Askeland, Pradeep P. Phule, 2006.
- Fatigue of Materials, Third Edition, Stephen S. Manson, 2007.