BR 3021 Shock Manual is a British military standard that defines the shock requirements and testing methods for equipment installed on naval ships and submarines. It was first published in 1978 and has been superseded by BR 8470 Shock and Vibration Manual in 2012. However, BR 3021 is still referenced by some other standards and specifications, such as D-03-003-007/SG-000 Canadian Forces Standard Specification for Shock Resistant Equipment on Naval Ships and Submarines.
The purpose of BR 3021 is to ensure that equipment can function properly and safely during and after an underwater explosion event, which can generate high impact shock loads on the ship structure and its components. BR 3021 consists of two volumes: Volume 1 covers the shock test requirements, including the test levels, procedures, equipment, and documentation; Volume 2 provides the design guidance for equipment foundations, including the calculation methods, criteria, and examples.
To use BR 3021, one needs to follow these steps:
Determine the shock grade of the equipment according to its location, function, and criticality on the ship or submarine.
Select the appropriate shock test level based on the shock grade and the type of equipment (rigid or resilient).
Prepare the test specimen, mounting arrangement, instrumentation, and test report according to the specifications in Volume 1.
Conduct the shock test using a suitable test machine, such as a floating platform, a pendulum hammer, or a drop weight.
Analyze the test results and verify that the equipment meets the performance and safety criteria.
BR 3021 is a useful reference for engineers and designers who work on naval equipment that needs to withstand high impact shock loads. It provides a consistent and reliable method for shock qualification and verification of equipment. However, it is important to note that BR 3021 is not a definitive document and may not cover all aspects of shock engineering. Therefore, it should be used in conjunction with other relevant standards and specifications, such as BR 8470, MIL-DTL-901E, MAP 01-470, etc.
One of the challenges of using BR 3021 is to select the appropriate shock test level for the equipment. BR 3021 defines four shock grades (A, B, C, and D) and four shock test levels (1, 2, 3, and 4) for each grade. The shock test level determines the peak acceleration and duration of the shock pulse that the equipment needs to withstand. The higher the shock grade and test level, the more severe the shock pulse.
The selection of the shock test level depends on several factors, such as the type of equipment (rigid or resilient), the mounting arrangement (fixed or flexible), the expected shock environment (near or far field), and the operational requirements (essential or non-essential). BR 3021 provides some general guidelines and tables for selecting the shock test level, but it also allows some flexibility and judgment based on engineering experience and analysis.
Another challenge of using BR 3021 is to conduct the shock test using a suitable test machine. BR 3021 specifies three types of test machines that can be used to generate the shock pulse: a floating platform, a pendulum hammer, or a drop weight. Each type of test machine has its own advantages and disadvantages, such as cost, availability, accuracy, repeatability, and scalability. BR 3021 provides some recommendations and limitations for each type of test machine, but it also requires some validation and calibration to ensure that the test machine can produce the desired shock pulse. 061ffe29dd