Shape and force control of prestressed cable-strut structures based on nonlinear force method

Yuan, Xiying; Liang, Xing; Li, Along

doi:10.1177/1369433216652411

Cited by 24 publications

(17 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A method is formulated to obtain a suitable actuator layout in order to control the structure into the target shapes. This method is a combination of stochastic search and a nonlinear force method (NFM) (Yuan, et al, 2016) in a nested optimization scheme.…”

Section: Outlinementioning

confidence: 99%

“…This idea made possible to formulate a computationally efficient routine based on the integrated force method (IFM) (Patnaik, et al, 2004) to obtain optimal actuator layouts for structures that adapt to loads through small shape changes (small deformation assumption). Yuan & Liang (Yuan, et al, 2016) presented a formulation called "nonlinear force method" (NFM) which was employed to obtain suitable actuation commands to control large shape changes. Computation of actuator commands was formulated as an iterative process which generally requires a low number of iterations to achieve convergence.…”

Section: Introductionmentioning

confidence: 99%

“…Computation of actuator commands was formulated as an iterative process which generally requires a low number of iterations to achieve convergence. However, in (Yuan, et al, 2016) no process was formulated to obtain the actuator placement, which was determined a priori.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Design of Structures That Adapt to Loads through Large Shape Changes

2020

View full text Add to dashboard Cite

Adaptive structures can modify their geometry and internal forces through sensing and mechanical actuation in order to maintain optimal performance under changing actions. Previous work has shown that wellconceived adaptive design strategies achieve substantial whole-life energy savings compared with traditional passive designs. The whole-life energy comprises an embodied part in the material and an operational part for structural adaptation. Structural adaptation through controlled large shape changes allows a significant stress redistribution so that the design is not governed by extreme loads with long return periods. This way, material utilization is maximized and thus, embodied energy is reduced. This paper presents a new design process for adaptive structures based on geometry and member sizing optimization in combination with actuator placement optimization. This method consists of two parts: (1) geometry and sizing optimization through sequential quadratic programming is carried out to obtain shapes that are optimal for each load case; (2) a formulation based on stochastic search and the nonlinear force method (NFM) is employed to obtain an optimal actuator layout and commands to control the structure into the target shapes obtained from (1). A case study of a planar statically indeterminate truss is presented. Numerical results show that 17% and 37% embodied energy savings are achieved with respect to an identical active structure designed to adapt through small shape changes and to a weight-optimized passive structure respectively. The combinatorial task of optimal actuator placement is carried out efficiently. The method formulated in this work produces actuator layouts which enable accurate geometric non-linear shape control under quasi-static loading through a low number of actuators compared to the number of members of the structure.

show abstract

Section: Outlinementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design of Structures That Adapt to Loads through Large Shape Changes

2020

View full text Add to dashboard Cite

show abstract

“…where S f and S d are the force and displacement sensitivity matrices (Senatore et al, 2019). In this work, S f and S d are computed using a force method based on singular value decomposition of the equilibrium matrix (Pellegrino, 1993;Luo and Lu, 2006;Yuan et al, 2016). Once the force and displacement sensitivity matrices are known, φ −1 is formulated as a constrained minimization of the difference between the controlled ( d c , f c ) and optimal configuration d t , f t :…”

Section: Actuation Layout Optimizationmentioning

confidence: 99%

“…Shape and force control of a reticular adaptive structure has been successfully tested in Senatore et al (2018); however, geometric non-linearity was not accounted for. Formulations of geometrically non-linear shape and force control exist (Yuan et al, 2016), nonetheless experimental validation is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Experimental Testing of a Small-Scale Truss Beam That Adapts to Loads Through Large Shape Changes

Reksowardojo

Senatore

Smith

2019

Front. Built Environ.

View full text Add to dashboard Cite

Adaptive structures have the ability to modify their shape and internal forces through sensing and actuation in order to maintain optimal performance under changing actions. Previous studies have shown that substantial whole-life energy savings with respect to traditional passive designs can be achieved through well-conceived adaptive design strategies. The whole-life energy comprises an embodied part in the material and an operational part for structural adaptation. Structural adaptation through controlled large shape changes allows a significant stress redistribution so that the design is not governed by extreme loads with long return periods. This way, material utilization is maximized and embodied energy is reduced. A design process based on shape optimization has been formulated to obtain shapes that are optimal for each load case. A geometrically non-linear force method is employed to control the structure into required shapes. This paper presents the experimental testing of a small-scale prototype adaptive structure produced by this design process. The structure is a simply supported planar truss. Shape adaptation is achieved through controlled length changes of turnbuckles that strategically replace some of the structural elements. The stress is monitored by strain sensors fitted on some of the truss elements. The nodal coordinates are monitored by an optical tracking system. Numerical predictions and measurements have a minimum Pearson correlation of 0.86 which indicates good accordance. Although scaling effects have to be further investigated, experimental testing on a small-scale prototype has been useful to assess the feasibility of the design and control methods outlined in this work. Results show that stress homogenization through controlled large shape changes is feasible.

show abstract