In a guided bend test, the sample is horizontally placed across two supports, and force is applied to the top of the midpoint, deforming the sample into a “U” shape. This test assesses the material’s response to applied stress.
What is a bend test?
A bend test, also known as the flexural test, is a standardized method employed to assess the ductility, bend strength, fracture strength, and resistance to fracture of materials. This testing methodology involves subjecting a specimen to a controlled bending force to evaluate its resistance to deformation.
The bend test is important in construction processes involving ductile materials subject to bending forces, in fact the absence of fracture during a bend test is indicative of the material’s ability to withstand similar stresses in real-world applications.
How to perform a bend test?
In order to properly conduct a bend test properly, there are several steps that must be followed, the first of which involves preparing the sample meticulously. This entails cutting a specimen to meet the specified dimensions, ensuring it accurately represents the material’s characteristics.
Once the sample is ready, the setup phase follows, wherein the specimen is strategically placed across two support anvils or mandrels to guarantee proper alignment.
Subsequently, the loading phase commences, gradually applying force to a designated region of the sample, inducing flexure. During this process, keen observation is essential as the material is monitored for any indications of deformation or fracture.
As the test progresses, recording results becomes imperative; noting the applied force at the point of deformation or fracture is crucial for comprehensive data collection.
Following the completion of the test, a thorough analysis of the results is undertaken, evaluating factors such as bend radius and material thickness to determine the material’s suitability for its intended application. This systematic approach ensures a comprehensive assessment of the material’s ductility and soundness through the bend test procedure.
What is the purpose of bend testing?
The purpose of bend testing lies in its ability to evaluate the flexibility and durability of materials, particularly metals. This mechanical test is essential for determining a material’s ductility, or its capacity to deform without fracturing. Widely employed in quality control processes during manufacturing, bend testing ensures that materials adhere to specific standards and performance criteria.
In welding, it plays a crucial role in qualifying procedures and assessing the quality of joints. Additionally, bend testing contributes to research and development efforts, aiding in the understanding of material behavior and suitability for diverse applications. By identifying defects such as cracks and irregularities, this testing method ensures the structural integrity of materials, making it a fundamental practice in various industries.
Types of bend tests
The most common bend tests are four.
A semi-guided bend test is a type of mechanical test where the specimen’s midpoint is bent to a specific angle or inside radius, providing insights into the material’s flexibility under controlled conditions.
The free bend test is a type of bend test that involves pushing the ends of the sample together without applying force to the bend itself. This test evaluates the material’s ability to withstand deformation without external support.
A common fracture toughness test, as per ASTM E399, involves a precracked starter crack on the bottom side of the midpoint. The sample is loaded into a 3-point bend fixture, applying force opposite to the fracture, gauging the material’s resilience.
Popular standards in bend testing
- ASTM C1161 Flexural Bend Ceramics Test Equipment
- ASTM E855 Bend Testing of Metallic Flat Materials for Spring Applications
- ASTM F1264 Torsion & Bend Fatigue Test Equipment for Intramedullary Fixation Devices
- ASTM F2193 Fatigue Bending Surgical Fixation Spinal Skeletal Test Equipment
- ASTM F383 Static Bend and Torsion Testing of Intramedullary Rods
- ASTM F384 Bending Fatigue Orthopedic Fixation Devices Test Equipment
- ASTM F564 Bending Fatigue Bone Staples Test Equipment
- ISO 7799 Metal Sheet and Strip Reverse Bend Test
- ISO 8491 Metallic Tube Bend Test Method EN
- ISO 10334 Tension Bending Torsion Suture Wire Test Equipment
- ISO 1288 Bending Strength of Glass
Bend testing machines
Linear motor testing machines