Frangibolt

Frangibolt 2018-02-08T23:23:58+00:00

SEE HOW IT WORKS!

TiNi’s Frangibolt actuators are a simple and effective way to support and release loads up to 20,000 lbf. The principle of operation is simple: A Shape Memory Alloy (SMA) cylinder elongates to fracture a bolt or stud thereby achieving separation of two or more components. Standard Fastener sizes range from # 8 size screws to ¾” bolts.

TiNi FRANGIBOLTs OFFER THE FOLLOWING ADVANTAGES:

Significant Flight Pedigree – Since its outer space debut aboard the spacecraft Clementine (1994), the Frangibolt has been qualified and used in numerous other space applications.

NEA (Non-Explosive Actuators) – 
As with all TiNi products, the Frangibolt is non-pyrotechnic and field reset-able with a minimum qualified life of 60 cycles.

Easy to Reset & Simple to Use – 
The actuator is reset by the customer in a matter of seconds (i.e. no need to ship back to TiNi). This enables numerous system level testing to be performed prior to flight usage to ensure maximum reliability.

Redundant – Each Frangibolt incorporates a redundant heater which is capable of independently functioning the actuator.

Safe to Use and Operate – The Frangibolt does not pose any safety concerns to personnel, is low shock, and insensitive to ESD (Electro-Static Discharge).

Cost Efficient – Due to its relative simplicity, TiNi Aerospace is able to provide the Frangibolt at a significantly lower price than comparable devices.

Frangibolt Options

ACTUATOR FC2

The FC2 size Frangibolt Actuator is designed to operate with a TiNi supplied #8 size Titanium Fastener (see below). These have a nominal tensile strength of 1,400 lbf (6,227 N) and are recommended for use in bolted joints which require up to 400 lbf (1,880 N) of preload. As with all TiNi products, key attributes include:

Features:

  • Non Pyrotechnic and Field Reset-able
  • Redundant Firing Circuit, and
  • Maximum Reliability Thru
    • Design Simplicity
    • Pedigree, and
    • Testability

* TiNi Aerospace must provide the specially notched Titanium fastener. This is largely application dependent and is readily manufactured to customer specification.

Function Time at Various Temperatures

Nominal values for estimation purposes only. Actual function time depends on application (joint) design and circuit used (primary or secondary).

FC2 Details

Specification subject to revision. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

ACTUATOR FC3

The FC3 size Frangibolt Actuator is designed to operate with a TiNi supplied #10 size Titanium Fastener (see below). These have a nominal tensile strength of 2,250 lbf (10,008 N) and are recommended for use in bolted joints which require up to 700 lbf (3,110 N) of preload. As with all TiNi products, key attributes include:

Features:

  • Non Pyrotechnic and Field Reset-able
  • Redundant Firing Circuit, and
  • Maximum Reliability Thru
    • Design Simplicity
    • Pedigree, and
    • Testability

* TiNi Aerospace must provide the specially notched Titanium fastener. This is largely application dependent and is readily manufactured to customer specification.

Function Time at Various Temperatures

Nominal values for estimation purposes only. Actual function time depends on application (joint) design and circuit used (primary or secondary).

FC3 Details

Specification subject to revision. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

ACTUATOR FC4

The FC4 size Frangibolt Actuator is designed to operate with a TiNi supplied 1/4″ size Titanium Fastener (see below). These have a nominal tensile strength of 5,200 lbf (23,131 N) and are recommended for use in bolted joints which require up to 1,500 lbf (6,670 N) of preload. As with all TiNi products, key attributes include:

Features:

  • Non Pyrotechnic and Field Reset-able
  • Redundant Firing Circuit, and
  • Maximum Reliability Thru
    • Design Simplicity
    • Pedigree, and
    • Testability

* TiNi Aerospace must provide the specially notched Titanium fastener. This is largely application dependent and is readily manufactured to customer specification.

Function Time at Various Temperatures

Nominal values for estimation purposes only. Actual function time depends on application (joint) design and circuit used (primary or secondary).

FC4 Details

Specification subject to revision. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

ACTUATOR FC6

The FC6 size Frangibolt Actuator is designed to operate with a TiNi supplied 3/8″ size Titanium Fastener (see below). These have a nominal tensile strength of 9,200 lbf (40,924 N) and are recommended for use in bolted joints which require up to 4,000 lbf (17,800 N) of preload. As with all TiNi products, key attributes include:

Features:

  • Non Pyrotechnic and Field Reset-able
  • Redundant Firing Circuit, and
  • Maximum Reliability Thru
    • Design Simplicity
    • Pedigree, and
    • Testability

* TiNi Aerospace must provide the specially notched Titanium fastener. This is largely application dependent and is readily manufactured to customer specification.

Function Time at Various Temperatures

Nominal values for estimation purposes only. Actual function time depends on application (joint) design and circuit used (primary or secondary).

FC6 Details

Specification subject to revision. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

ACTUATOR FC8

The FC8 size Frangibolt Actuator is designed to operate with a TiNi supplied 1/2″ size Titanium Fastener (see below). These have a nominal tensile strength of 15,000 lbf (66,723 N) and are recommended for use in bolted joints which require up to 7,000 lbf (31,130 N) of preload. As with all TiNi products, key attributes include:

Features:

  • Non Pyrotechnic and Field Reset-able
  • Redundant Firing Circuit, and
  • Maximum Reliability Thru
    • Design Simplicity
    • Pedigree, and
    • Testability

* TiNi Aerospace must provide the specially notched Titanium fastener. This is largely application dependent and is readily manufactured to customer specification.

Function Time at Various Temperatures

Nominal values for estimation purposes only. Actual function time depends on application (joint) design and circuit used (primary or secondary).

FC8 Details

Specification subject to revision. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

Frangibolt Accessories

FRANGIBOLT RESET TOOLS

All of TiNi Frangibolts are rated to have a minimum life of 60 cycles. For continued testing and preparation for installation, TiNi provides a range of Frangibolt reset tools as shown. These are made up of a high quality hydraulic pump, cylinder and pressure gage designed to generate the force and stroke required to compress the actuator.

Compression of the Frangibolt actuator is a simple 3 step process: First, install the unit in the fixture as shown. Second, pump the handle until the prescribed pressure is reached. Third, release the pressure via the bleed screw and remove the actuator. The whole process may be carried out in less than 30 seconds. Furthermore, the size and weight of the Frangibolt Compression Fixture make it fully portable allowing easy transport.

Reset Tool Details for TiNi Frangibolt Options

Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

FASTENERS

The Fasteners used in the Frangibolt release system are an integral part of the mechanism. For all Frangibolt sizes, a significant amount of testing was performed to derive the optimum material, notch profile and notch diameter. These features must remain constant for all applications. The customer typically specifies the Fastener type, grip and thread length as well as the notch location. TiNi Aerospace Fasteners are manufactured per strict tolerances and procedures involving both individual and lot-level testing and inspection.

The picture below illustrates some of the more common Fastener configurations that have been successfully used. Each suits a different type of Frangibolt joint design and lends enormous versatility to this unique product.

*Fasteners are made from 6AL-4V Titanium per AMS 4965 with a minimum tensile strength of 160 Ksi (1104 MPa) Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

Fastener Examples

WASHERS

The Washers used in the Frangibolt assembly are an important part of the mechanism. They serve the following critical functions:

  • They distribute the relatively high recovery stress generated by the Nitinol cylinder during actuation, on a much larger contact area.
  • They have minimum thickness so as to minimize the overall length of the joint.
  • They have chamfers specially designed to match fillet radiuses of NAS bolts (at the location where the bolt head meets the bolt shank).
  • They have tighter fitting inner diameters designed to clear NAS bolt shanks while at the same time maximizing coverage of the Nitinol cylinder.

Product Details

*Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

LOCK NUTS

Standard Frangibolt Models may require the use of a locknut as part of a release mechanism design.

TiNi Aerospace offers custom locknuts or NAS1805 series locknuts which are commonly used as part of a Frangibolt release mechanism design.

The NAS1805 series locknuts have been widely used with the larger sized Frangibolt release mechanisms as they offer the following key features:

  • They are made from high strength A286 stainless steel with a minimum tensile strength of 180 ksi.
  • They are silver plated to reduce friction and minimize galling.
  • They have a locking feature in the form of deformity in the thread.
  • They offer a higher profile then other similar sized locknuts, thereby increasing the number of threads engaged and reducing the stress in the thread.

TiNi custom locknuts are recommend for use with the smaller sized Frangibolt release mechanisms as they offer the following key features:

  • They are made from high strength Titanium Ti 6Al-4V STA (Solution Treated and Aged) with a minimum tensile strength of 160 ksi.
  • They are anodized for ease of identification and further material hardening.
  • They have a locking helicoil made out of 304SS (Stainless Steel) with a minimum tensile strength of 200 ksi.
  • They offer a higher profile then other similar sized locknuts, thereby increasing the number of threads engaged and reducing the stress in the thread.

Note that not all Frangibolt release mechanism designs require a locknut as many designs thread directly into a flange or surface. In this case, it is important that the threaded connection be designed to withstand the tensile strength of the notched Frangibolt fastener.

Product Details

*Torque specification is recommended value above running.
Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

ENCLOSURE

The enclosure shown is a generic design meant to show how the Frangibolt can be held down and retained after actuation. This is done using a thin walled aluminum housing which is held down using a low profile ring. Note that making these 2 parts as separate pieces allows the enclosure to be rotated into the exact position desired for each application. A third component in the form of a silicon rubber dampener is incorporated inside the can to avoid metal on metal impact during actuation.

In many cases a separate enclosure (as shown) is not necessary because such a means can be designed directly into the releasable joint.

Product Details

*Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

SWITCH WASHERS

The Switch Washer is a combination Switch and Washer developed as a simple means of determining when the Frangibolt has functioned. It comprises of a top and bottom bearing surface, internally mounted belleville spring, and a pair of mating electrical contacts. The belleville spring is preloaded to generate more than 20 lbs of force to keep the top and bottom surfaces separated thereby firmly biasing the switch to the Open position. However, once installed on a bolted joint and tightened to the prescribed torque, the top and bottom surfaces are brought together closing the switch contacts and preloading the Frangibolt joint assembly. The switch contacts remain closed until the Frangibolt releases the tension by breaking the bolt during actuation. At this time, the belleville spring once again returns the Switch back to the Open position within a fraction of a second.

The Switch-Washer may be used in one of two ways: It can be wired in series with the Frangibolt actuator to act as an automatic shut-off switch, or it can be wired as part of a separate circuit to serve as a feedback loop to a controller.

Product Details

*Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

INSTRUMENTED FASTENERS

For applications which require strict control of preload, TiNi Aerospace has teamed with Strainsert Co. to manufacture Frangibolt fasteners which are fully instrumented. These offer the following advantages:

  • Control Preload within 1%.
  • Allow for measurement of In-Situ loads during testing (for example during thermal cycling and/or vibration testing).
  • Can be used as feedback to register successful deployment (i.e. preload goes to 0 when bolt is broken).

Product Details

*Note: All values are approximate and for reference only. Contact TiNi Aerospace for detailed ICD (Internal Control Drawing).

Still want to learn more?

VISIT OUR FAQ

How can we assist in your project?

CONTACT US FOR A CUSTOM SOLUTION