The purpose of the shock fragility analysis is to determine the maximum mechanical shock levels the product can withstand before damage occurs. Damage can be physical breakage, electronic malfunction, or aesthetic damage. The end result of the shock fragility test is a Damage Boundary plot which shows the maximum acceleration and velocity change envelope likely to cause damage to the product. This information is used to determine weak or sensitive components within the product, the ability of the product to meet the published or designed specifications levels. It also provides information necessary for package design and testing purposes.

Vibration fragility analysis is generally limited to identification of natural or resonant frequencies within the product rather than stressing the product at higher and higher levels until damage occurs. The end result of the vibration test is a series of transmissibility plots which essentially "map" the vibration sensitivity of the product in each axis. With this information, fatigue sensitive components and those prone to vibration related failures can be identified and corrected. In addition, the data is extremely useful for package design and testing purposes.

APT engineers have been instrumental in the development and use of product fragility analysis including various alternate approaches to data collection. Different products may demand creative approaches to the task of fragility assessment. APT has extensive experience in this area and offers this knowledge to our customers as part of the testing service. We believe that integrity is the priceless element in any test. We strive to conduct the appropriate test in a conscientious manner and to report the result sin a clear, concise format with recommendations when appropriate.

The vibration sensitivity of the product is determined by testing according to the requirements of ASTM D3580 or similar test procedures. To conduct the test, the product is rigidly fixed to the table of a vibration test machine after accelerometers have been mounted on flexible or critical components within the product. The product is then subjected to a low level (5 G is typical) sinusoidal resonant search over the frequency band of interest, typically 5-500 Hz. The response of the various monitored components is plotted as a function of frequency resulting in a transmissibility graph. This graph shows the peak acceleration response as a function of frequency and the amplification reached at resonance. This test is repeated for all flexible or critical elements in each axis. With the appropriate controller and analysis capability, the test can also be conducted using random vibration inputs in addition to or in place of sinusoidal inputs. In either case, the end result is a series of transmissibility plots describing the natural or resonant frequency of various components and the amplification reached at resonance.

During this phase of testing, a product is subjected to vibration and shock inputs until a failure occurs -- a fragility level. This information tells StorageTek APT engineers the exact level of durability of a product and adds the next link of information for package design.