Industries like automotive and construction require a powerful test that helps determine a material's toughness. Not only its ability to bend, but also to absorb energy when there's an impact without breaking. That's why the Charpy test is still commonly practiced today. However, the thing we need to highlight here is the application of Charpy impact test.
Why is that? This test uses a swinging pendulum to measure a material's toughness. Although the formula is quite simple, it requires proper setup and calibration to achieve accurate results. Let Qualitest guide you to learn more in this article.
What Is the Charpy Impact Test?
Charpy test is one of the most common impact tests that is still practiced in the vehicle sector, critical structures, or in any industrial sector using metals. The application of Charpy impact test is quite simple but reliable. This becomes the fundamental reason why this test is still relevant ever since it was developed in 1905 by Georges Charpy.
The objective of this test is to determine whether the material is considered tough enough, not just in enduring pressure but also when it's struck. Let’s say in the automotive industry, this becomes one of the checkpoints that helps determine the safety level of spare parts and vehicles before they are tested and launched in the market.
Likewise, when we're talking about bridge structures, the Charpy impact test helps determine whether the structure is strong enough and reliable, so engineers can project the ability of the construction to withstand day-to-day use.
Why Charpy Impact Testing Matters
The application of Charpy impact test proves its value by evaluating crashworthiness and the structural toughness of structures. It simply gives engineers a reliable way to assess how much energy a material can absorb.
Here’s why it matters so much:
- Crash Energy Absorption
In vehicle design, the Charpy test helps measure how well a material can manage energy in a crash, which is vital for both structural integrity and passenger safety.
- Material Selection in Harsh Conditions
Materials like Stainless Steel 304 and Aluminum Alloys 6061-T6 and 7075-T6 are often tested using Charpy to determine if they can handle real conditions like extreme temperatures and stress.
- Aerospace-Grade Strength Testing
High-performance alloys used in aerospace need a balance of strength and weight. Charpy tests help verify that materials like 7075-T6 can deliver on both.
- Toughness Validation for Structural Components
From railway tracks to bridges, ensuring the material won’t suddenly fracture under stress is a must. Charpy testing reveals if the material is up to the job.
- Instrumented Data for Deeper Insight
With the use of strain gauges and digital sensors, the instrumented Charpy test captures detailed mechanical responses. This gives engineers a more clear picture of how materials deform and fail under impact.
Key Applications of Charpy Impact Testing
Understanding application of Charpy impact test helps in verifying if a new alloy can take an impact and offers critical data for informed decision-making. Here’s how the Charpy impact test is typically applied:
1. Specimen Preparation
A standard specimen is machined to the dimensions of 127 mm × 12.7 mm with a V-notch (2.54 mm deep, 45° angle). Not without strong reason, this meant to create a stress concentration that encourages fracture during testing.
2. Mounting the Specimen
The notched specimen is positioned horizontally between the machine’s supports (anvils). Meanwhile, the notch is positioned facing away from the pendulum to simulate realistic tension scenarios.
3. Pendulum Release
A calibrated pendulum is released from a set height. It swings down and strikes the center of the specimen, to simulate sudden impact.
4. Measuring the Energy
Source: Journal of Engineering and Technological Sciences
After impact, the machine automatically records the energy absorbed by the specimen as it fractures. The difference in the pendulum’s height before and after impact is used to calculate the absorbed energy using the conservation of energy formula:
E= m×g×(h1−h2) − Efriction
Where:
- E = energy absorbed (joules)
- m = pendulum mass (kg)
- g = 9.81 m/s² (gravity)
- h1 = starting height (m)
- h2 = rebound height (m)
- Efriction = energy lost to friction (joules)
Let’s say the Charpy impact tester uses a pendulum with a mass of 20 kg. The pendulum is raised to an initial height (h₁) of 1.4 meters, and after striking the specimen, it swings up to a final height (h₂) of 0.9 meters. Assume the energy lost to friction is 1.8 joules.
We can now calculate:
- Potential energy before impact:
20 × 9.81 × 1.4 = 274.68 joules
- Potential energy after impact:
20 × 9.81 × 0.9 = 176.58 joules
- Now subtract the energy after impact and friction loss from the initial energy:
E = 274.68 – 176.58 – 1.8 = 96.3 joules
So, the specimen absorbed 96.3 joules of energy during the impact. This absorbed energy reflects the toughness of the material.
The higher the number, the more energy the material can absorb before breaking. It means, it is more suitable for applications involving impact or crash conditions.
5. Optional Step: Temperature-Controlled Testing
For more advanced testing, the Charpy impact test can also be performed in controlled temperature environments. Especially for evaluating material toughness in cold climates or elevated heat conditions, this additional step is usually practiced following the main steps of the Charpy impact test.
Charpy Impact Test vs. Other Material Tests
Now you’ve learned about the application of Charpy impact test. The next thing to understand is how the Charpy test is compared to other material tests.
Charpy impact test is considered a destructive test, which means that the material sample is permanently damaged after the impact. This happens because the test intentionally pushes the material to its failure point to evaluate how much energy it can absorb before breaking
On the other hand, there's the Izod impact test, which is closely related to Charpy. While both aim to measure material toughness, they differ in setup, sample orientation, and application. Charpy is commonly used for metals in industries like automotive or railway, whereas Izod is more popular for testing plastics and lighter composites.
Let’s compare them side-by-side:
Aspect | Charpy Impact Test | Izod Impact Test |
Test Type | Destructive: breaks sample | Destructive: breaks sample |
Sample Position | Horizontal, supported at both ends | Vertical, clamped at one end |
Notch Direction | Faces away from the pendulum | Faces the pendulum |
Typical Materials | Metals like steel, alloys | Plastics, composites |
Common Applications | Automotive, railway, construction | Packaging, plastics, consumer goods |
Test Standard | ASTM E23 | ASTM D256 |
Energy Range | Higher (150–300 J) | Lower (up to 124 J) |
Reusability of Sample | No | No |
Cost Efficiency | Moderate: higher for setup and larger samples | Lower: ideal for small, lightweight samples |
How U.S. Companies Use Charpy Impact Testing for Compliance and Quality
In the United States, the application of Charpy impact tests lead industries to meet strict safety and performance standards. Besides supporting material selection, the test also helps to ensure the success rate of projects.
Here’s to picture how different U.S. industries apply Charpy testing:
1. Automotive
U.S. automotive manufacturers, especially those working on crash-tested components like bumpers, chassis, or side panels, use Charpy testing to confirm that materials can withstand sudden forces. This ensures vehicles pass FMVSS (Federal Motor Vehicle Safety Standards) and meet insurance industry safety benchmarks.
2. Manufacturing
General manufacturing facilities across the country rely on Charpy tests to assess welding integrity, joint performance, and pipe strength. This is commonly practiced especially in oil, gas, and heavy machinery industries. This ensures compliance with ASME and ANSI standards for industrial safety and reliability.
3. Construction
In the construction sector, Charpy testing helps engineers evaluate the durability of steel, concrete reinforcement bars, and composites used in bridges, buildings, and infrastructure. U.S. DOT and state agencies often require these tests to meet AASHTO or ASTM standards.
4. Defense
For military-grade equipment, Charpy tests are essential to determine the toughness of armor plating, vehicle shielding, and ballistic materials. The U.S. Department of Defense and its suppliers use this data to ensure protective systems can absorb shock from explosive or ballistic impact.
Final Thoughts
In the field, we may encounter many factors often overlooked during the application of the Charpy impact test. For example, like improper machine calibration or misinterpreting the calculation results.
Since the majority of industries that require this test involve high-risk applications, such oversights can lead to severe consequences. Qualitest provides globally standardized Charpy impact testers, ranging from models for testing metals and plastics to supporting tools like notch projectors.
Explore our full range of impact testers in our product catalog, and consult to our experts to help you select the most suitable solution for your industry.
Reference:
1. Zainuddin, H., et al. (2024). Investigation of impact properties under instrumented Charpy test. Journal of Engineering and Technological Sciences.
