Technology & Applications Overview

E-truss represents a new class of deployable/folding truss structure characterized by modular construction, simplicity, and ability to retract axially (length-wise) into a compact unit with no loose parts . They have the characteristic high strength, low-weight and stiffness of conventional trusses. In summary the two major advantages which provide for an excellent cost/benefit ratio are:

• Quick deployment from a compact transportable package, and

• Ability to readily fold back into a compact state for ease of transport and stowage.

As a foldable structural system, its versatility comes from its modular nature and the availability of several cross sections - square, rectangular, triangular, trapezoidal, and hexagonal, including trusses that incorporate flat panels. Deployment, as a free module or an end-mounted extendible beam consists of expanding the truss axially (10x to 20x) until the folding chords lock and the structure becomes a load-carrying unit. This is typically done manually but can be power-driven.

HOW IT WORKS
GEOMETRIC CHARACTERIZATION

TRUSS DATA SHEETS

S-1 BASIC SQUARE SECTION
S-2 RECTANGULAR
S-3 SQUARE SECTION
S-4 TRIANGULAR
S-4P RECTANGULAR
S-5 TRAPEZOIDAL
S-6 HEXAGONAL

APPLICATIONS OVERVIEW
LOAD CAPACITY AND CONSTRUCTION
MANUFACTURING CONSIDERATIONS AND COST FACTORS

CURRENT DEVELOPMENT STATUS
INVESTORS AND LICENSING PATENT STATUS

HOW IT WORKS

The basic folding principal is that of "orthogonally-hinged" truss frames and joints, causing synchronous coordinated motion analogous to a scissor mechanism, except that unlike a scissor linkage, truss chords are formed to create a load-carrying truss structure. The joint axes always remain orthogonal to the truss axis producing the desired stable motion. (U.S. Patent 7,028,442 and patents pending)

GEOMETRIC CHARACTERIZATION

The following describes each truss structure by numbers of truss faces, internal diagonals, and chords.

TRUSS DATA SHEETS

S-1 BASIC SQUARE SECTION The S-1 represents the basic folding structure from which all the other trusses are derived in the E-truss/P-truss structural system. It comprises 3 planar trusses that are rigidly connected at common joints . It requires no internal bracing. In addition to its use as a beam or mast it is well-suited for work platform applications, forming floor and side rails. >>More
S-2 RECTANGULAR The S-2 rectangular truss, patent pending, is derived from the S-1. It comprises two S-1 sections with the common chord s omitted to create X-bracing. It also requires no internal bracing. >>More
S-3 SQUARE SECTION The S-3 is a closed square truss formed from two mated S-2 sections. Common chords and internal diagonals are omitted. All 4 sides have X-bracing.
S-4 TRIANGULAR The S-4 triangular truss , patent pending, is also derived from the S-1 open section truss. Chords can fold internally using the patented orthogonal joints of the S-1 truss. Generally , it is well suited for masts and booms, and can form a curved profile. >>More
S-4P RECTANGULAR Our new rectangular S-4P truss or P-truss, derived from the S-1, can deploy flat panels which fold compactly within the truss members. The panel edges are the folding chords. The panels fold and unfold in a "z-fold" pattern. Well-suited for solar PV panels, personnel platforms, and compact-stowage quick-deploy structural beams. When used as a personnel platform or bridge the floor panels do not have to be added separately. It can be configured as a beam or column/mast by using folding chords in lieu of panels. >>More
S-5 TRAPEZOIDAL This truss, patent pending, combines two S-4 triangular trusses. A common center chord is formed. It is well-suited for area platforms, with decking panels added as required. >>More
S-6 HEXAGONAL This truss has a hexagonal cross section and 6 chords, and is derived from the S-2 rectangular truss creating 6 faces at 120 deg angles. Generically it is used as beam, column, or enclosure frame for deployable habitats deployed quickly by crane or helicopter.

APPLICATIONS OVERVIEW

This chart shows candidate applications by class or type and selected trusses by cross section. S-1,S-2, etc. To view application examples, click the links shown.

MANUFACTURING CONSIDERATIONS AND COST FACTORS E-truss and P-truss structures are most economical for quantity production. A typical truss has only a few basic parts and subassemblies such as the hinge joints, tubular members, and latches - which are identical for each truss bay. These lend themselves well to quantity production and optional robotic assembly. • Typical manufacturing and assembly operations employ waterjet or plasma cutting, jig welding and/or mechanical fastening of fittings and tubing, and final assembly of subassemblies. The modular bays are hinged together as required, and end frames are added. For the S-4p panel truss, panels are typically welded or riveted. • Fabrication and assembly operations are somewhat similar to those for commercial scissor lifts whose manufacturing is a well-established economical process for folding structures, and there is commonality with fabrication of scaffolding structures in regard to the use of cast aluminum fittings and swage-joining to tubular members. • Cost data is not yet well-established, but dependent on production volumes. These structures are intended for applications in which the direct and indirect cost benefits of efficient transport & stowage, and rapid set-up outweigh the added cost over equivalent non-folding structures (equivalent size, load capacity, stiffness, endurance, etc). These added costs are those associated with use of hinged joint fittings and pins. • Direct benefits are those associated primarily with schedule time and labor savings which can result in early payback . Indirect benefits are those in which compactness and quick deploy/tear-down are essential when dictated by time and space limitations.

(The above photo and the two below where taken at NASA-KSC.)

DEVELOPMENT STATUS Merrifield Engineering has established an extensive database of: • Design drawings: preliminary, conceptual, and fabrication-level • CAD models and parametric layouts, • Design algorithms to create various truss configurations and features, • Structural finite-element models and kinematic models, • Structural and kinematic test data, • Manufacturing options and processes, • Component and fastening/joining processes, and • Engineering models for test validation and demonstration.

Using this database, we have created configurations and design options for a large number of applications. A number of such applications are illustrated and described in this website. Our technology is currently protected by a primary U.S. patent, with three U.S. patents pending.

Our industrial co-developer, United Space Alliance, has an extensive database of hardware drawings, CAD models, structural and dynamic models. They maintain development-level truss assemblies, components, test fixtures, and instrumentation. A 21 ft Platform for critical servicing of flight vehicles has been thoroughly analyzed and tested under service conditions.

To date, we have jointly tested several configurations of the S-1 and S-2 trusses as deployable platforms & towers. Formal structural testing was performed on end-supported, cantilever-mounted and base-mounted/ center-mounted configurations, along with weld testing and component load/deflection testing. This has included special mounting platforms, preloaded joint testing, and a limited degree of powered actuation testing.

We can offer validated design concepts within our multi-truss system of modular structures as described earlier in our website, and we continue to evaluate new truss designs, components, and applications for industrial, commercial, military, disaster-relief, marine, and aerospace markets.

© 2014 Merrifield Engineering, Inc.