Introduction to Mechanical properties test of plastic
Plastics are a diverse group of materials with a wide range of mechanical properties. While the specific properties can vary depending on the type of plastic, there are some general characteristics that can be described.
1. Strength: Plastic materials typically have a lower strength compared to metals and ceramics. They are generally less rigid and more flexible. However, some engineering plastics, such as reinforced or composite plastics, can have higher strength and stiffness.
2. Elasticity: Plastics exhibit elasticity, which means they can deform under applied stress but return to their original shape when the stress is removed. The degree of elasticity can vary among different types of plastics, with some being more flexible and resilient than others.
3. Ductility: Many plastics are ductile, meaning they can undergo plastic deformation before fracture. This property allows them to be shaped and formed through processes like injection molding or extrusion.
4. Hardness: The hardness of plastics can vary widely depending on the type and composition. Some plastics are relatively soft and can be easily scratched or indented, while others are harder and more resistant to deformation.
5. Toughness: Plastic materials generally possess good toughness, meaning they have the ability to absorb energy and resist fracture. This property makes them suitable for applications where impact resistance is important.
6. Creep: Plastics have a tendency to slowly deform over time when subjected to a constant load or stress. This behavior is known as creep and is an important consideration in designing plastic components for long-term applications.
7. Thermal expansion: Plastics typically have a higher coefficient of thermal expansion compared to metals. This means they expand and contract more with temperature changes, which can be important to consider in applications with varying temperature conditions.
It is important to note that these properties can vary significantly depending on the specific type of plastic, its composition, processing techniques, and any additives or reinforcements used. Therefore, it is crucial to consult specific material data sheets or conduct thorough testing to determine the mechanical properties of a particular plastic.
Purpose of the Mechanical properties test in Plastic
The mechanical properties of plastics serve a crucial purpose in various industries and applications. They enable engineers and designers to select suitable materials, optimize product designs, ensure structural integrity, choose appropriate manufacturing processes, enhance performance and durability, and prioritize safety considerations. Understanding the strength, elasticity, ductility, hardness, toughness, creep resistance, thermal expansion, friction and wear properties, and environmental resistance of plastics allows for informed decision-making, leading to the development of functional, reliable, and safe plastic components or products.
List of the Mechanical properties test in plastic
(1). TENSILE TESTS (ASTM D 638, ISO 527-1)
Tensile tests, as described by ASTM D 638 and ISO 527-1 standards, are widely used to evaluate the mechanical properties of materials under tension. These tests involve subjecting a standardized specimen to a steadily increasing axial load until it fractures or reaches a predetermined deformation. The test measures parameters such as tensile strength, elongation at break, and Young's modulus, providing valuable information about a material's strength, ductility, and stiffness. The specimens, typically in the form of dogbone-shaped samples, are clamped into a testing machine and subjected to a uniaxial force, applying tension along the longitudinal axis. During the test, force and elongation measurements are recorded, allowing for the determination of stress-strain behavior, which provides insights into the material's structural integrity and performance. The results obtained from tensile tests are crucial for material selection, quality control, and engineering design considerations across various industries.
(2). FLEXURAL PROPERTIES (ASTM D 790, ISO 178)
Flexural properties, as defined by ASTM D 790 and ISO 178 standards, are used to assess the bending behavior and stiffness of materials. These tests involve applying a three-point or four-point bending load to a standardized specimen, measuring its resistance to deformation and the resulting stress-strain characteristics. The specimens, typically rectangular or prismatic in shape, are supported on two points or three points, respectively, creating a span under which the load is applied perpendicularly. By gradually increasing the load, the test determines parameters such as flexural strength, flexural modulus, and deflection at a given load. These properties provide valuable insights into a material's ability to withstand bending stresses, its structural rigidity, and its suitability for applications requiring resistance to flexural forces. The results obtained from flexural tests are widely used in materials selection, quality control, and design considerations across various industries, including construction, automotive, and aerospace.
(3). COMPRESSIVE PROPERTIES (ASTM D 695, ISO 75-1 AND 75-2)
Compressive properties, as outlined by ASTM D 695 and ISO 75-1/75-2 standards, are utilized to evaluate the behavior of materials under compressive loads. These tests involve subjecting a standardized specimen to a steadily increasing axial force applied in the opposite direction of its longitudinal axis until failure or a predetermined deformation is reached. The tests measure parameters such as compressive strength, compressive modulus, and deformation characteristics under compression. The specimens, often cylindrical or prismatic in shape, are placed in a compression testing machine and loaded with a force that compresses the specimen along its longitudinal axis. The resulting stress-strain behavior provides valuable insights into a material's ability to withstand compressive forces, its structural stability, and its suitability for applications that require resistance to compression. The data obtained from compressive tests are widely used in material selection, quality control, and engineering design considerations in industries such as construction, manufacturing, and structural engineering.
(4). IMPACT TESTING
Impact testing is a mechanical testing method used to evaluate the behavior of plastic materials under sudden loading or impact conditions. It involves subjecting a specimen to a high-energy impact force and measuring its response to determine parameters such as impact strength, energy absorption, and fracture toughness. The test typically involves striking the specimen with a pendulum hammer or drop weight system and measuring the energy absorbed or the resulting deformation caused by the impact. Impact testing helps assess a plastic material's ability to withstand and dissipate energy during impact, indicating its resistance to fracture, cracking, or brittle failure. The results obtained from impact testing aid in material selection, design optimization, and quality control processes in industries such as automotive, aerospace, and consumer goods, where plastics are used in applications prone to impact or dynamic loading.
(1). IZOD–CHARPY IMPACT TEST (ASTM D-256, ASTM D4812 ISO 179)
The Izod-Charpy impact test, conducted according to ASTM D-256, ASTM D4812, and ISO 179 standards, is a widely employed method to assess a material's resistance to impact and toughness. The test involves striking a standardized notched or unnotched specimen with a pendulum hammer, and measuring the energy absorbed or the resulting deformation caused by the impact. The test determines parameters such as the Izod impact strength or the Charpy impact strength, which indicate the material's ability to withstand sudden loading and resist fracture under impact conditions. The specimens, typically in the form of rectangular bars, are clamped in a pendulum impact testing machine, and the hammer is released to strike the specimen. The energy absorbed or the resulting deformation is then measured, providing valuable information about a material's toughness, durability, and its suitability for applications where impact resistance is critical. The Izod-Charpy impact test is widely used in industries such as automotive, construction, and manufacturing, where materials may be subjected to sudden impacts or dynamic loading.
(2). CHIP IMPACT TEST (ASTM D4508)
The chip impact test, defined by ASTM D4508 standard, is a method used to evaluate the impact resistance of coating materials or finished surfaces. This test simulates the impact of a small flying object, such as a stone or debris, on the surface of a material. A pneumatic-driven device propels the test specimen, which consists of a coated panel, towards a stationary target covered with an abrasive surface. The panel impacts the target at a specific velocity, and the resulting damage, such as chipping, cracking, or delamination, is visually assessed and quantified. The chip impact test helps assess the durability and protective capabilities of coatings, providing valuable information for applications in automotive, aerospace, and industrial sectors where materials are exposed to potential impact hazards. The results of the test aid in material selection, quality control, and improvement of coating formulations to enhance their impact resistance properties.
(3). TENSILE IMPACT TEST
The Tensile Impact Test is a mechanical testing method used to assess the impact resistance of materials under tensile loading conditions. Although there isn't a specific ASTM standard for this test, it is commonly conducted by subjecting a test specimen to a sudden tensile force while simultaneously applying an impact load. The test combines elements of both tensile and impact testing to evaluate the material's ability to withstand sudden, high-energy impacts while under tension. The test typically involves impacting the specimen with a pendulum or drop weight system while it is being pulled apart in a tensile testing machine. The result of the test is typically measured in terms of energy absorbed or the maximum force sustained by the specimen before failure. The Tensile Impact Test helps assess a material's performance in scenarios where it may experience sudden dynamic loading while being stretched or pulled, such as in automotive crashworthiness evaluations or other impact-prone applications.
(4). HIGH-SPEED IMPACT TEST (ASTM D3763, ISO 6603-2)
The High-Speed Impact Test, conducted according to ASTM D3763 and ISO 6603-2 standards, is a testing method used to evaluate the impact resistance and energy absorption characteristics of plastic materials or products under high-speed impact conditions. The test involves subjecting a specimen to a rapid and controlled impact using a pendulum or other suitable impact device. The specimen is typically in the form of a flat panel or a molded shape, and it is securely clamped or supported during the test. The impact device is released, and it strikes the specimen with a specified energy or velocity. The resulting deformation, fracture, or other damage to the specimen is observed and quantified. This test provides valuable information about a material's ability to withstand sudden, high-speed impacts and its potential for use in applications where impact resistance is critical, such as in automotive components or protective equipment. The results obtained from the high-speed impact test assist in material selection, design optimization, and quality control processes.
(5). MISCELLANEOUS IMPACT TESTS
Miscellaneous impact tests encompass a range of specialized testing methods used to evaluate the impact resistance and performance of materials or products in specific applications. These tests are not governed by specific ASTM or ISO standards but are developed based on industry-specific requirements or internal protocols. Examples include the drop impact test, where a specimen is dropped from a specified height to assess its ability to withstand impact forces and potential damage; the ball impact test, which involves propelling a steel ball at high velocity onto a material or product to simulate impacts from flying objects and evaluate resistance to penetration, cracking, or deformation; and various industry-specific impact tests tailored to assess the impact behavior of materials and products in specific contexts. These miscellaneous impact tests provide valuable insights into the durability, reliability, and safety of materials and products, aiding in material selection, product design, and quality assurance processes across different industries.
(5). SHEAR STRENGTH (ASTM D 732)
Shear strength, as defined by ASTM D 732 standard, is a measure of a material's resistance to shearing or sliding forces that act parallel to the plane of its cross-section. The test involves applying a force perpendicular to the plane of the specimen to induce shear stress until failure occurs. The specimen is typically in the form of a rectangular or circular shape, and it is securely clamped or supported during the test. The force is applied gradually, and the maximum force or stress required to cause failure is recorded as the shear strength. Shear strength is an important mechanical property that provides insights into a material's ability to withstand lateral or sliding forces, making it particularly relevant in applications where materials may experience shear loads, such as in fasteners, adhesives, or structural components. The shear strength test, as per ASTM D 732, plays a crucial role in material selection, quality control, and engineering design considerations, enabling the assessment of a material's structural integrity and performance under shear loading conditions.
(6). ABRASION (ASTM D 1044)
Abrasion testing, as specified by ASTM D 1044 standard, is a widely used method for evaluating the abrasion resistance of materials. The test involves subjecting a flat specimen to controlled abrasive action under specified conditions. A rotating abrasive wheel or other suitable abrasive medium is applied to the specimen surface with a constant or progressively increasing load. The specimen is subjected to a specified number of revolutions or a predetermined abrasive cycle. After testing, the specimen is inspected for visible damage, such as scratches, wear, or loss of material. The test measures parameters such as weight loss, volume loss, or changes in surface roughness, providing valuable information about a material's ability to withstand abrasive wear and its durability in real-world scenarios where contact with abrasive substances or surfaces is expected. The results obtained from abrasion tests aid in material selection, quality control, and performance optimization in industries such as automotive, flooring, coatings, and textiles, where abrasion resistance is a critical factor.
(7). FLEXURAL FATIGUE TEST (ASTM D 671)
The Flexural Fatigue Test, defined by ASTM D 671 standard, is a testing method used to evaluate the fatigue behavior and durability of materials under repeated bending or flexural loading conditions. The test involves subjecting a rectangular specimen to cyclic loading that induces alternating tensile and compressive stresses on the material. The specimen is typically in the form of a beam or bar, and it is supported at two points while a cyclic bending load is applied at the center. The test continues until the specimen fails or reaches a predetermined number of cycles. The number of cycles to failure or the fatigue life of the material is recorded. This test provides valuable information about a material's resistance to fatigue failure, its ability to withstand repeated loading without significant degradation or failure, and its durability in applications where cyclic bending stresses are present, such as in structural components or mechanical parts subjected to dynamic loads. The results obtained from the flexural fatigue test assist in material selection, design optimization, and quality assurance processes, ensuring the reliability and performance of materials in real-world fatigue conditions.
(8). HARDNESS TEST
Hardness testing is a widely used method to determine the resistance of a material to indentation or penetration by an indenter. It provides an indication of the material's hardness, which is its ability to resist deformation or surface indentation under an applied load. Various hardness testing methods exist, such as the Rockwell, Brinell, Vickers, and Shore hardness tests, each utilizing different indenter types and testing procedures. In general, the test involves applying a known load to the material's surface for a specified duration and measuring the depth or size of the resulting indentation. The hardness value obtained from the test enables comparisons between different materials or different regions of a material, allowing for material selection, quality control, and assessing the material's suitability for specific applications. Hardness testing is widely employed across industries, including manufacturing, engineering, automotive, and construction, to ensure product quality, durability, and performance.
(1). ROCKWELL HARDNESS (ASTM D 785)
The Rockwell Hardness Test, as specified by ASTM D 785 standard, is a commonly used method to determine the hardness of a material. This test involves measuring the depth of penetration of an indenter into the material under the application of a minor and major load. The Rockwell hardness test utilizes different scales, such as A, B, C, D, E, F, G, H, K, and L, each associated with specific indenter types and loads. The test procedure involves applying the minor load, followed by the major load, and then measuring the depth of penetration or the difference in depth before and after the major load application. The hardness value is determined based on the scale and the depth measurement. The Rockwell hardness test provides a reliable and convenient method to assess the hardness of various materials, including metals, plastics, and composites. It is widely used in quality control, material characterization, and selection processes across industries such as manufacturing, aerospace, automotive, and construction, where hardness is a critical property for evaluating the performance and durability of materials.
(2). DUROMETER HARDNESS (ASTM D 2240)
The Durometer Hardness Test, defined by ASTM D 2240 standard, is a widely used method for measuring the hardness of elastomeric and rubber-like materials. This test determines the resistance of a material to indentation by a specified durometer indenter. The durometer hardness is expressed as a numerical value on a scale ranging from 0 to 100, with higher values indicating greater hardness. The test involves pressing the indenter into the material under a specific force and for a specified duration, and the depth of penetration or the indenter rebound is measured. The test is typically performed using durometers with different scales, such as Shore A and Shore D, depending on the hardness range of the material being tested. The Durometer Hardness Test provides a quick and non-destructive method to assess the hardness of elastomeric materials, enabling quality control, material selection, and performance evaluation in various industries, including automotive, aerospace, construction, and manufacturing.
(3). BARCOL HARDNESS TEST (ASTM D 2583)
The Barcol Hardness Test, specified by ASTM D 2583 standard, is a test method used to measure the hardness of non-metallic materials, particularly those with a relatively low Shore hardness value. This test is commonly applied to measure the hardness of fiberglass-reinforced plastics (FRP) and other similar materials. The Barcol hardness value is obtained using a handheld instrument called a Barcol Impressor, which features a pointed indenter and a spring-loaded mechanism. The test involves pressing the indenter against the material surface with a fixed force and measuring the depth of penetration. The Barcol hardness value is determined based on the resistance encountered during indentation. This test provides a quick and portable method for evaluating the relative hardness of non-metallic materials, aiding in material selection, quality control, and assessment of material uniformity in industries such as marine, aerospace, and construction, where FRP and similar materials are extensively used.
