Real-World Applications of Thermal Property Testing

Thermal conductivity is an extremely important material property that enables thousands of production systems to function properly and efficiently. Without it, life would not be as simple as it is today.

The thermal properties of materials are largely determined by their structure, density, and composition. This is why it is important to test a material's thermal properties as thoroughly as possible to understand how it will behave under real-world conditions.

Thermal Stress Testing

Thermal stress testing is an effective method for evaluating the safety limits of a material or product at various temperatures. It can also be used to assess the expected lifespan of a component or material in an application.

Differential scanning calorimetry (DSC) is a standard method of testing the thermal properties of a solid or liquid. It provides data on a wide range of parameters, including specific heat capacity (SHC), melting point, crystallization temperature, glass transition temperature, and heat of vaporization, in addition to characteristic mass loss, decomposition time and oxidation induction time.

A thermogravimetric analysis (TGA) method is another important tool in measuring the thermal properties of a solid or a liquid. TGA can determine the characteristic mass loss and decomposition pattern of a material over time, as well as determining the percentage of organic or inorganic components.

Test systems from edevis for thermal stress analysis (TSA) record and visualize the mechanical stresses dynamically introduced into components on a test bench, which can be useful for comparing simulations or providing accurate material parameters. It can also be used to detect crack growth or track fracture propagation in test specimens.

Using the latest infrared camera technology, TSA accurately records even the smallest changes in ambient temperature while tensile or compressive stresses are applied to components on the test bench. This allows the test to detect cracks and their propagation, as well as track failure behaviour in real time with high resolution.

This method is often used in conjunction with concentric ring flexure testing to measure material strength parameters. The flexure test is carried out by placing the sample in contact with a metal-cooling rod, which is heated to a specified temperature.

Thermal Expansion Testing

When temperatures increase, objects and materials can expand or contract in response to the change. Understanding the nature of thermal expansion is important for engineering, architecture, and science applications. It’s also an important component of scientific literacy.

One of the most popular real-world applications of thermal property testing is dilatometer testing, which identifies the coefficient of thermal expansion for solids. This test can be performed with a variety of material types, including flexible materials such as fabrics and laminates.

Using a dilatometer to measure a material’s coefficient of thermal expansion is a convenient way to understand how the materials react to temperature changes. A sample of a metal, such as stainless steel, can be placed in the dilatometer and heated at a set temperature.

This method can be used to determine the expansion coefficient for a wide range of metals, including aluminum and copper. This type of testing is a valuable tool for identifying the materials that will work best in a particular application.

A dilatometer can also be used to measure the thermal expansion of solids, such as cement. This method can be useful for evaluating the thermal expansion of rock in high-temperature reservoirs and for determining the thermal expansion coefficient of concrete samples in mining or civil projects.

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Thermal Conductivity Testing

Thermal conductivity is one of the most important metrics to know when it comes to predicting how well an insulator will transfer heat. It is an important factor to consider for a wide range of engineering applications, including building insulation and metal-alloy computer chip heatsinks.

Various methods can be used to measure the thermal conductivity of materials, depending on their intended use and capability. These include steady-state or non-steady-state techniques and transient heat transfer techniques. These types of measurements differ in technique, material type, specimen size, measurement time and capability [5, 6].

Steady-state techniques rely on a known temperature difference between two specimens placed on either side of a guarded hot plate apparatus. The guarded heaters help to minimize lateral heat transfer and concentrate the heat flow to the specimens. The combined specimens' thermal conductivity is then calculated based on the main heater's power, the total thickness of the two specimens and the auxiliary heater's temperature.

Transient methods are also useful in evaluating the thermal conductivity of solids, such as metals and ceramics, as well as other thin films. These methods use a sensor system and a special mathematical model to describe the thermal conductivity of the test specimen. The modified transient plane source (MTPS) method is the most common of these methods and can be used to measure thermal transport properties for a range of different kinds of materials, including both isotropic and anisotropic materials.

The MTPS measurement system uses a spiral shaped wire, which is both a heating element and a temperature sensor, to record the change in thermal conductivity over a set amount of time. The system also has a guard ring to approximate uni-directional heat transfer.

Thermal Shock Testing

Despite the advances in technology, products still rely on thermal shock testing to ensure that they can stand up to sudden temperature variations. If a product can withstand these rapid shifts without compromising its performance, it is considered marketable and can be sold to consumers.

A wide range of industries use thermal shock chambers to test the durability of their components and systems against extreme environmental conditions. This includes micro-electronic and electrical firms, automotive and aerospace companies, and telecommunications manufacturers.

Thermal shock tests involve rapid and severe temperature variations that can cause physical elements to shatter, crack, or bind in unintended ways. These sudden shifts are meant to mimic, in an accelerated environment, the wear and tear a product will encounter in normal or standard use.

In air to air thermal shock tests, test samples are repeatedly subjected to rapidly alternating high and low temperatures.

This enables manufacturers to develop reliable devices that can withstand these harsh conditions. A typical air to air thermal shock test takes less than ten seconds.