Ahmed Manguri, Domenico Magisano, Robert Jankowski
{"title":"Gradient-Based Weight Minimization of Nonlinear Truss Structures With Displacement, Stress, and Stability Constraints","authors":"Ahmed Manguri, Domenico Magisano, Robert Jankowski","doi":"10.1002/nme.70096","DOIUrl":"https://doi.org/10.1002/nme.70096","url":null,"abstract":"<p>This paper presents an effective and robust computational method of gradient-based methodology for weight minimization of geometrically nonlinear structures, considering 3D trusses as exemplary case study. The optimization framework can accommodate multiple different constraints: (i) bounds on the cross-sectional area of each design element, (ii) prescribed ranges for displacements and stresses, and (iii) nonlinear stability for geometries such as arches and domes. For large structures, this results in numerous optimization variables and constraints, including the highly nonlinear (ii) and (iii). Such constraints are evaluated consistently and simultaneously by combining path-following finite element analysis and null vector method. Typically, the gradient of the nonlinear structural response is approximated numerically, which is computationally intensive and can introduce inaccuracies deteriorating the optimization process. In contrast, this work derives a fully analytical gradient evaluation for nonlinear deformation, stress, and stability constraints. This is implemented directly within the finite element solver, enhancing robustness and computational efficiency of the optimization. Validation examples range from simple benchmarks to large structures.</p>","PeriodicalId":13699,"journal":{"name":"International Journal for Numerical Methods in Engineering","volume":"126 14","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/nme.70096","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144716693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Product of Exponentials (POE) Splines on Lie-Groups: Limitations, Extensions, and Application to \u0000 \u0000 \u0000 S\u0000 O\u0000 (\u0000 3\u0000 )\u0000 \u0000 $$ SO(3) $$\u0000 and \u0000 \u0000 \u0000 S\u0000 E\u0000 (\u0000 3\u0000 )\u0000 \u0000 $$ SE(3) $$","authors":"Andreas Müller","doi":"10.1002/nme.70088","DOIUrl":"https://doi.org/10.1002/nme.70088","url":null,"abstract":"<p>Existing methods for constructing splines and Bézier curves on a Lie group <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation>$$ G $$</annotation>\u0000 </semantics></math> involve repeated products of exponentials deduced from local geodesics, w.r.t. a Riemannian metric, or rely on general polynomials. Moreover, each of these local curves is supposed to start at the identity of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation>$$ G $$</annotation>\u0000 </semantics></math>. Both assumptions may not reflect the actual curve to be interpolated. This paper pursues a different approach to construct splines on <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation>$$ G $$</annotation>\u0000 </semantics></math>. Local curves are expressed as solutions of the Poisson equation on <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation>$$ G $$</annotation>\u0000 </semantics></math>. Therewith, the local interpolations satisfies the boundary conditions while respecting the geometry of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation>$$ G $$</annotation>\u0000 </semantics></math>. A <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 <mtext>th</mtext>\u0000 </mrow>\u0000 <annotation>$$ kmathrm{th} $$</annotation>\u0000 </semantics></math>-order approximation of the solutions gives rise to a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 <mtext>th</mtext>\u0000 </mrow>\u0000 <annotation>$$ kmathrm{th} $$</annotation>\u0000 </semantics></math>-order product of exponential (POE) spline. Algorithms for constructing 3rd- and 4th-order splines are derived from closed form expressions for the approximate solutions. Additionally, spline algorithms are introduced that allow prescribing a vector field the curve must follow at the interpolation points. It is shown that the established algorithms, where <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 <mtext>th</mtext>\u0000 </mrow>\u0000 <annotation>$$ kmathrm{th} $$</annotation>\u0000 </semantics></math>-order POE-splines are constructed by concatenating local curves starting at the identity, cannot exactly reconstruct a","PeriodicalId":13699,"journal":{"name":"International Journal for Numerical Methods in Engineering","volume":"126 14","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/nme.70088","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}