Andrea Incardona, Material Engineer at Instron, explores how tensile impact testing helps engineers simulate real-world conditions, spot weaknesses before failure and build safer, more reliable products.
Instron
Today’s large automotive components are designed to meet growing technical demands such as improved crash energy absorption and reduced vehicle weight. They usually use hybrid materials like carbon fibre-reinforced polymers (CFRP) or multilayer structures like aluminium-plastic composites. These often behave unpredictably under high strain rates, making mechanical characterisation difficult under real-world conditions like crash events.
In contrast, electronic materials like thin polymer films, adhesives or ceramics are smaller and demand more precise testing. Even minor cutting defects during specimen preparation or alignment errors during testing can skew results beyond expected tolerances.
Real-world environmental conditions introduce additional variables during material characterisation testing. For example, dashboards and phone casings experience thermal swings from intense summer heat to freezing winter mornings. These fluctuations affect material properties and must be accounted for.
The test setup is critical. Some plastics deform gradually under stress, while others fail suddenly. Gripping methods, specimen geometry and impact velocities must reflect real-world conditions. A test that doesn’t simulate field conditions may miss critical weaknesses.
Why tensile impact tests matter
Tensile impact testing evaluates how materials behave under sudden loads, guiding material choice and product design.
In automotive crashes, crumple zones must absorb energy without cracking. In electronics, battery components, films and battery components must withstand impact, heat and dynamic stress without losing integrity.
Often, a material’s failure mode matters as much as its strength. Car interior components might be needed to shatter into small, non-lethal fragments for safety. In consumer electronics, repeated drop testing helps predict performance and lifespan under real-world conditions.
Testing procedures also differ by sector. Automotive materials typically use dog-bone-shaped specimens, suited to larger, stiffer samples. In contrast, electronics favour strip-shaped specimens for thin, flexible polymers, as they reduce stress concentrations and better reflect real use.
Drop tower systems are a common tool for tensile impact testing. These provide controlled, repeatable impact velocities across a wide range of impact energies. In a typical setup, the specimen is gripped vertically between fixtures, and a weighted striker is dropped from a specified height to apply a sudden tensile load, simulating real-world dynamic stress events like crashes or drops.
Digital image correlation (DIC) can be integrated with drop tower testing to enhance outputs by mapping strain fields in real time. This is especially useful for composites, where force measurements alone may not capture local deformations due to the material’s high anisotropy.
Instron’s 9450 Drop Tower system addresses these challenges with a versatile velocity range of 0.77 to 24 m/s and selectable impact energies between 0.3 and 1.800 J.
Accessories for tensile impact testing include integrated load cells measuring forces from 0.45 to 30 kN, ensuring high accuracy in low- and high-force applications from films to composite materials.
The 9450 also integrates with high-speed cameras and DIC software, producing CAE-ready (computer-aided engineering) data to help engineers optimise designs and reduce physical prototyping needs.
How tensile impact testing enhances material design
Tensile impact testing guides engineers in materials selection at every stage, from raw polymer formulation to choosing the most suitable processing method. For example, nanoporous polymer films in lithium-ion batteries must balance porosity for ion transfer with the strength necessary to maintain functionality.
Testing across strain rates and temperatures helps fine-tune mechanical properties for safe, reliable performance. In plastics, tensile impact testing can reveal the glass transition temperature, informing design decisions that enhance durability and safety.
From thin films in electronics to reinforced structures in vehicles, tensile impact testing bridges the gap between material science and real-world performance. Simulating dynamic impact loads helps engineers identify failure modes early, refine designs and choose the appropriate materials.