{"title":"Exact solutions of the Euler–Bernoulli equation for selected polynomially non-uniform beams used for acoustic black holes","authors":"Antonin Krpensky, Michal Bednarik","doi":"10.1016/j.ijsolstr.2025.113468","DOIUrl":null,"url":null,"abstract":"<div><div>In this work, we present a method for obtaining exact analytical solutions to the Euler–Bernoulli equation for nonuniform beams with continuously varying rectangular cross-sections. The approach is based on factorizing the fourth-order equation into a system of second-order differential equations with variable coefficients. Focusing on polynomial expressions for the cross-sectional profile, we show that such factorization is possible only when the profile is described by a polynomial of at most third order. In the general cubic case, the resulting equation transforms into Heun’s differential equation; in degenerate cases, it reduces to the hypergeometric or Bessel equations, all of which admit closed-form solutions. To demonstrate the method’s applicability, we compute reflection coefficients for selected profiles relevant to Acoustic Black Holes and validate the analytical results using a Riccati-based numerical method, showing excellent agreement.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":"320 ","pages":"Article 113468"},"PeriodicalIF":3.4000,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Solids and Structures","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0020768325002549","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
In this work, we present a method for obtaining exact analytical solutions to the Euler–Bernoulli equation for nonuniform beams with continuously varying rectangular cross-sections. The approach is based on factorizing the fourth-order equation into a system of second-order differential equations with variable coefficients. Focusing on polynomial expressions for the cross-sectional profile, we show that such factorization is possible only when the profile is described by a polynomial of at most third order. In the general cubic case, the resulting equation transforms into Heun’s differential equation; in degenerate cases, it reduces to the hypergeometric or Bessel equations, all of which admit closed-form solutions. To demonstrate the method’s applicability, we compute reflection coefficients for selected profiles relevant to Acoustic Black Holes and validate the analytical results using a Riccati-based numerical method, showing excellent agreement.
期刊介绍:
The International Journal of Solids and Structures has as its objective the publication and dissemination of original research in Mechanics of Solids and Structures as a field of Applied Science and Engineering. It fosters thus the exchange of ideas among workers in different parts of the world and also among workers who emphasize different aspects of the foundations and applications of the field.
Standing as it does at the cross-roads of Materials Science, Life Sciences, Mathematics, Physics and Engineering Design, the Mechanics of Solids and Structures is experiencing considerable growth as a result of recent technological advances. The Journal, by providing an international medium of communication, is encouraging this growth and is encompassing all aspects of the field from the more classical problems of structural analysis to mechanics of solids continually interacting with other media and including fracture, flow, wave propagation, heat transfer, thermal effects in solids, optimum design methods, model analysis, structural topology and numerical techniques. Interest extends to both inorganic and organic solids and structures.