Some Performance Trends in Hierarchical Truss Structures

Murphey, Thomas W.; Hinkle, Jason

doi:10.2514/6.2003-1903

“…However, we will not make use of the (approximate) simplified analysis of repetitive structures with a discrete field approach or as a continuum (Noor, 1988). Another way of building structures from elementary units is hierarchical, which is the main subject of hierarchical structure analysis and design (Ashby, 1991;Lakes, 1993;Murphey and Hinkle, 2003;McEachen et al, 2004). From these contributions it appears that hierarchical structures can be very beneficial, in that they make improvements of orders of magnitude possible in structural properties.…”

Section: Introductionmentioning

confidence: 97%

Stiffness of planar tensegrity truss topologies

Jager

¹

,

Skelton

²

2006

International Journal of Solids and Structures

View full text Add to dashboard Cite

This paper proposes and demonstrates a symbolic procedure to compute the stiffness of truss structures built up from simple basic units. Geometrical design parameters enter in this computation. A set of equations linear in the degrees-of-freedom, but nonlinear in the design parameters, is solved symbolically in its entirety. The resulting expressions reveal the values of the design parameters which yield desirable properties for the stiffness or stiffness-to-mass ratio. By enumerating a set of topologies, including the number of basic units, and a set of material distribution models, stiffness properties are optimized over these sets. This procedure is applied to a planar tensegrity truss. The results make it possible to optimize the structure with respect to stiffness properties, not only by appropriately selecting (continuous) design parameters like geometric dimensions, but also by selecting an appropriate topology for the structure, e.g., the number of basic units, and a material distribution model, all of which are discrete design decisions.

show abstract

“…The simplified equations for three longeron trusses with one diagonal per face are identical to Equations (6) except that GA and GJ are multiplied by ½, …”

Section: Previous Effective Continuum Equation Derivationsmentioning

confidence: 99%

Symbolic Equations for the Stiffness and Strength of Straight Longeron Trusses

Murphey¹

2006

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials ConferenceSelf Cite

4
0
0
0

View full text Add to dashboard Cite

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)AFRL/VSSV SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. (Clearance #VS06-0160) SUPPLEMENTARY NOTESAuthor's final manuscript, published in the proceedings of the 47 th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 1-4 May 2006, Newport, RI ABSTRACTSymbolic equations for the effective continuum stiffness and strength properties of several periodic beam-like trusses have been previously derived and are well documented in the literature. These equations are useful because they allow for rapid design and assessment of structures that would otherwise require a more time-consuming analysis. Previous investigations have considered changes in truss construction, such as the number of longerons and diagonal lacing as discrete cases; unique sets of equations were derived for each unique construction. These equations did not restrict the relative sizes of longerons, diagonals and battens. In the present work, a generic set of equations is derived that is applicable to trusses with an arbitrary numbers of longerons and diagonal lacings, however, the diagonals must be soft relative to the longerons and battens. The resulting equations are useful in preliminary truss sizing and optimization routines because they allow the number of longerons and diagonals to be changed by simply changing the value of a constant in the equations. In this paper, equations are derived for effective continuum beam bending, torsion, shear and axial loading. Within the assumption of relatively soft diagonals, the equations are shown to be equivalent to the three, four and six longeron results previously published by Renton and are numerically verified through comparison to finite element analysis solutions. Symbolic equations for the effective continuum stiffness and strength properties of several periodic beam-like trusses have been previously derived and are well documented in the literature. These equations are useful beca...

show abstract

“…where C 11 , C 12 , C 13 , C 14 , C 21 , C 22 , C 23 and C 24 are arbitrary constants and λ 11 and λ 21 are the magnitudes of the roots of the characteristic polynomial ψ 11 and ψ 21 given, respectively by λ 11 = P c (EI) 1 and λ 21 = P c (EI) 2…”

Section: Solutions For Column Bucklingmentioning
confidence: 99%

Manufacture and Experimental Analysis of a Concentrated Strain Based Deployable Truss Structure
Mejia-Ariza¹,
Murphey²,
Pollard³
2006
47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials ConferenceSelf Cite
4
0
1
0
View full text Add to dashboard Cite

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information ABSTRACTA truss structure was built and tested to advance deployable structures technology based on the concentrated strain approach. In 3 rd order hierarchy systems, this architecture has the potential to provide a 10 fold improvement in mass efficiency, and demonstrate a linear compaction ratio that is five times better than current technology. A 101.6 cm x 12.7 cm x 12.7 cm test article was fabricated, and a buckling test and analysis was performed. The total mass of the deployable truss structure was 28 grams. This structure was constructed of piecewise constant cross section elements. One of the components consisted of highmodulus pull-truded carbon fiber rods (CFRs) for the majority of the length. The other components were compliant flexure joints made of Nitinol NiTi, a shape memory alloy (SMA) capable of a repeatable superelastic strain of 5.0% at either boundary. The results of this research provide a contribution to the deployable structures science by improving the compaction ratio and the mass efficiency of deployable structures without decreasing the truss performance limits. SUBJECT TERMS

show abstract

Some Performance Trends in Hierarchical Truss Structures

Cited by 38 publications

References 9 publications

Stiffness of planar tensegrity truss topologies

Stiffness of planar tensegrity truss topologies

Symbolic Equations for the Stiffness and Strength of Straight Longeron Trusses

Manufacture and Experimental Analysis of a Concentrated Strain Based Deployable Truss Structure

Contact Info

Product

Resources

About