Dynamically loaded bolts and fasteners play a vital role in the aerospace and automobile industries, and even in automotive racing applications. Fasteners subjected to alternating loads are commonly found in combustion engines, aircraft turbines, landing gears and in the structural airframe components.

The desired design goal of these fasteners is to provide adequate joint strength, low weight and fatigue resistance. Therefore, dynamic testing of the fasteners and bolted structures is required to ensure proper materials properties and manufactured quality.

Fatigue testing in research and development applications is necessary to understand the behavior of fasteners which are constructed with new materials or manufacturing processes.

The fasteners are tested at various loads to determine a “S-N” curve or endurance limit generally up to several million load cycles. The Zwick Vibrophore provides a cost-effective method for performing these dynamic tests.

Its electromagnetic resonant operation results in high-testing frequencies with low energy and maintenance requirements. The high testing frequencies shorten overall testing durations and therefore allow important quality or development projects to be supported in an efficient manner. For example, the test duration for 2 million load cycles and a testing frequency of 120 Hz is less than 5 hours. Intervention by the user is only necessary when changing specimens, which can be done simply and safely. The set-up, control and monitoring of the test procedure is conducted by the testing software testXpert.

After the operator loads the sample in the machine, the desired testing parameters are input into testXpert®, including the static preload and loading rate, alternating load (or displacement), desired number of cycles, end-test criteria. After the test is started, the test parameters are displayed and updated on an online graph within testXpert®. The software provides various possibilities for post-test data evaluation, e.g., the compilation of an individual testing procedure, or export into Excel or Word.

Naturally, the Vibrophore is also suited for use in other dynamic tests to determine the fatigue endurance and fatigue strength of materials and even components such as connecting rods, camshafts, crankshafts, chains, and other components subject to repetitive loading. The Vibrophore may also be used for fracture toughness (KIc) testing.

The nominal force of a Vibrophore varies between 5 and 500 kN, depending on the model, and test frequencies generally range between 80 and 300 Hz – generally much faster than for servo-hydraulic systems at only 5% of the energy requirement. Due to the fast testing speeds, low energy costs and low maintenance, the Vibrophore has a rapid return on its original capital investment.

Zwick offers a full line of accessories for the Vibrophore including grips, bend fixtures, fixturing to allow torsional fatigue, strain and extensometry, and environmental chambers.

Consider a Zwick Vibrophore to meet the requirements of your next dynamic test program!