Fastener Verification Solution for the Space Industry

Space boltSpaceBolt is the software for bolt verification according to space industry standards (ECSS-HB-32-23). Starting as the internal development at Space Structures GmbH, it was successfully evaluated and procured by ESA and Airbus Defence and Space, and became the commercial product which significantly increases the productivity of mechanical engineers.

Bolted joints are one of the most common connection methods in structural engineering. Although their fundamental parameters are well known after centuries of use, structural failures relating to bolts continue to occur.

In practice, one of the most important aspects when dealing with bolted connections is the preload. Various effects, including the scatter of the friction coefficients, tightening method and condition of the thread lead to a scatter in the preload. Moreover, it is important not only to know the scatter but also to ensure that sufficient preload is actually applied. For this purpose, torque-tension tests and bolt elongation measurements are often performed.

The importance of the standards for the bolted connections cannot be overestimated. However, calculation procedures presented in these standards (VDI-2230, ECSS-E-HB-32-23) tend to be quite lengthy and complicated. A common approach is to implement relevant calculations in spreadsheets and reuse them later on. Experience shows this approach is not robust: the spreadsheets are poorly validated and can become inconsistent due to constant modifications required to adapt them to new projects. In addition, results of such spreadsheet analyses are often difficult to check for an independent reviewer. In order to overcome these problems, it is beneficial to use specialized tools for the bolt calculations.

Several software solutions for bolt calculations are available on the market. However, for their effective application in the space industry an additional adaptation reflecting margins of safety philosophy and other aspects specific to space projects is needed. Moreover, these tools are often focused on a single bolt loaded with a particular load; therefore the verification of systems with multiple bolted connections for a set of loading scenarios requires intense engineering efforts.

While performing bolt verifications and reviewing the supplied documentation, Space Structures GmbH has developed an in-house tool for bolt calculations – SpaceBolt. The primary requirements for the software were compliance to the space industry fastener verification standard ECSS-E-HB-32-23 and an efficient user experience. The software was constantly used internally during different projects ranging from mechanical ground support equipment (MGSE) to large spacecraft structures and was continuously improved based on the first-hand feedback.

Later, Jena Optronik GmbH noticed the potential of SpaceBolt and decided to use it in their projects. This indicated a need for such a tool in the space industry and the logical step was to engage with the ESA. After a thorough evaluation and verification, the tool was procured by the structures section of ESA.

Today, SpaceBolt helps engineers in a number of companies to design MGSE, electronic and optical units, and satellite structures spanning from CubeSats to large spacecrafts. All customers, but most significantly Airbus Defence and Space, have reported the tool helps to significantly improve the bolt calculation process and increase productivity. The feedback from the community is continuously implemented in the software for its further improvement.

Some of the SpaceBolt features include:

  1. Transparent and ESA-validated calculation procedures based on the relevant industry standards.
  2. Complete documentation of the results for simple report generation.
  3. Integration with Finite Element Analysis (FEA) software allowing calculations based on the actual loads rather than artificial overly conservative load cases.
  4. An intuitive user interface enabling effective handling of a large number of bolts and loads.
  5. A centralized database of the geometrical, material and friction data.
  6. Generation of the data for fracture analysis, for example with NASGRO.
  7. Different preload definition methods.
  8. The modular licensing structure enabling customers to select only the necessary modules and thus maximise cost-efficiency.

Space Structures GmbH will be exhibiting at Space Tech Expo Europe 2017 in stand G82