Poor Flange Structural Design Can Kill Bolted Joint Performance

Poor Flange Structural Design Can Kill Bolted Joint Performance

Overview

The ubiquity of bolted joints is a testament to their performance as non-permanent joints. However, this often leads to complacency in their design. Why would something so cheap be worth much design attention? And so, bolted joint failures are still commonplace.

In particular, the role of the flange design in determining bolted joint capacity is not considered as deeply as it should. Constraints often push creative designers to fit bolted joints into bizarre configurations in order to meet space or assembly requirements. Ingenium has catalogued a series of common mistakes seen in our years of consulting to help you avoid repeating them.  These include:

  1. Thin flanges
  2. Poorly balanced bolt patterns
  3. Gaps in the preload loop
  4. Multi-plane flanges
  5. Radially-oriented bolts

For more information regarding this subject use the form below to request a copy of the source paper.  Our experienced design team can assist you in efficiently reaching an optimum solution to your design challenges.

CH-47 Helicopter Blade Fold Gearbox

CH-47 Helicopter at Sunset

The Challenge

Ingenium was commissioned to develop a design concept to modify existing CH-47 Chinook blade fold gearboxes. The design was required to add automatic blade folding capability to the existing manual fold functionality.

As is often the case with projects adding functionality to existing designs; this design required the incorporation of several new parts without compromise of existing features. In this case the manual ‘wrench driven’ mode was retained while the ability to fold the blades with a motor was added. This new capability in turn required the incorporation of new fault and overload protection features.

While the brief was challenging it was made more so by the very short execution time provided.

The Solution

Ingenium has the resources to assign highly experienced engineers and manage them effectively. By matching the appropriate skills and experience with specific project needs we are able to proceed through a thorough trade study and design process in a very short order. Ingenium put together a team of mechanical experts to focus on this project and were able to design this “add on” gearbox within only a few weeks.

Outcome

Ingenium met the customer’s expectations providing a concept trade study and final design proposal in the limited time available. The package included optimized pricing, drawings, analyses, and technical descriptions.

Infinitely Variable Transmission

Infinitely Variable Transmission

The customer was pursing the development of concepts with a view to increasing the fuel efficiency of large commercial vehicles. One such concept was the possibility of using infinitely variable transmission to achieve bi-directional power transmission while optimally matching the engine speed to accessories.
The infinitely variable transmission had to be very efficient, reliable for thousands of hours, compact, lightweight, and cost effective. And, to provide all these qualities in a harsh environment.

The Solution

Ingenium applied its experience with many different types of infinitely variable transmissions used in different modes of transportation and industrial applications to a comprehensive trade study. The study was designed and conducted to determine the best type of transmission for the unique requirements of the fuel economy enhancing system. At its conclusion, a multi-mode hydromechanical approach was down selected.
The concept was developed into a full-fledged design layout including sizing of the transmission components. Ingenium’s team also developed a system simulation model to quantify the efficiency improvements and to evaluate the fuel consumption reduction that the system could provide over several different vehicle duty cycles.

Outcome

As a result of the successful design study the customer was able to proceed with prototype development. Ingenium provided a comprehensive technical design and data package to support the customer’s testing program. Ingenium also provided training to the customer’s team to enable them to further evaluate potential vehicle performance enhancements.

Machine Disconnect

Machine Disconnect

The Challenge

As a result of new FAA requirements our customer was presented with a challenging requirement to provide fault isolation on a rotating machine on a commercial aircraft.  A clutch or disconnect mechanism was required, but as minimal space was available an innovative new approach for disconnecting a high-speed shaft was needed.  Given the limited amount of time available the customer reached out to Ingenium.

The Solution

Ingenium put together a team to create concept designs for over 30 potential mechanisms and performed a trade study to select an optimal solution based on multiple figures of merit including size, cost, development risk, and performance.

The team, comprising design engineers, analysts, metallurgists, electrical engineers, manufacturing engineers, dynamics experts, and project engineers generated a detailed design of the chosen concept including a structural analysis and ANSYS non-linear transient analysis.  Following review with the customer the team proceeded to produce models, drawings, tolerance stack-ups, detailed structural and thermal analysis, materials, and process specifications for the design, including the innovative trigger mechanism.

Using our rapid prototyping capabilities Ingenium quickly manufactured and assembled prototype test units, delivering test units ahead of schedule. Ingenium’s SMEs and project engineers collocated at the customer’s facilities to support and document the results of the development testing in their facilities and finalize the production configuration.  Ingenium subsequently supported formal qualification testing and production units are currently flying.

Outcome

Ingenium was able to rapidly establish a rapport with the customer and evaluate the detailed nature of their challenge. Ingenium identified an innovative solution to a set of new requirements using a process driven approach. The design concept was successfully taken to full prototype realization and subsequent qualification in an ambitious timeframe as required by the overall program constraints.

Our service offering, as is often the case, included the customer owning the patent and design intellectual property for the device.  We are pleased to observe the customer applying the technology to other products within their portfolio.