With issue 9 of the 100th volume of the Zeitschrift für Angewandte Mathematik und Mechanik we continue the publication of special papers devoted to the anniversary. The paper Ludwig Föppl and Gerhard Schubert: Unknown Classics of Contact Mechanics written by E. Popova and V. L. Popov highlights an outstanding but mostly unknown contribution of Ludwig Föppl and Gerhard Schubert to contact mechanics. Both of two main techniques of the powerful method described in this paper go back to Ludwig Föppl. In 1941, L. Föppl published a method of determination of elastic deformations under the action of an arbitrary axisymmetric load. Importantly, the two key equations of this formulation had a form allowing for simple inversion, and thus provided a complete solution of the contact problem for an arbitrary axisymmetric punch. This inversion was made in the dissertation of Schubert under supervision of Prof. Föppl.

Karl Ludwig Föppl [1] was at that time professor of Mechanics at the Technische Hochschule München (now University of Technology Munich). The history of this chair is related to several famous scientists: the first holder was Johann Bauschinger [2], followed by August Otto Föppl [3] ‐ Ludwig Föppl's father. In 1922 Ludwig Föppl was appointed as the third chair holder, followed by Heinz Neuber [4], Horst Lippmann [5] and EwaldWerner (the current chair holder). At present, the chair is renamed: Lehrstuhl für Werkstoffkunde und Werkstoffmechanik (Institute of Materials Science and Mechanics of Materials).

Ludwig Föppl had an intensive relationship with the ZAMM – as a member of the Editorial Board and author of several papers on continuum mechanics, structural mechanics, contact mechanics and photoelasticity. It should be mentioned that within the one hundred years history of ZAMM only once it happened that a member of the editorial board (August Föppl was a board member from the beginning) was substituted by his son (Ludwig Föppl was a member of the board from 1924) Figure 1.

G. Schubert published a shortened version of his above‐mentioned dissertation in the “Ingenieur‐Archiv” (today Archive of Applied Mechanics). This famous and now well‐established journal was founded by R. Grammel in 1929 (first issue December 1929). In contrast to the ZAMM, whose focus lies in the interaction of Mathematics and Mechanics, the “Ingenieur‐Archiv” was devoted to the interaction between Mechanics and Mechanical and Civil Engineering. The paper of G. Schubert was published in 1942 and met the same fate as many papers of the ZAMM of that time: due to the political situation in Germany only a few researchers studied publications published by German researches and written in German.

As the paper by Schubert presents the best overview of the methods proposed by Föppl, the paper by E. Popova and V.L Popov is mostly devoted to this paper and also contains its complete translation into English.

随着《时代精神与机械化》杂志第100卷第9期的发布，我们将继续发表纪念周年的特别论文。论文路德维希·福珀（LudwigFöppl）和格哈德·舒伯特（Gerhard Schubert）：接触力学的未知经典由E. Popova和VL Popov撰写的论文突出了LudwigFöppl和Gerhard Schubert对接触力学的杰出贡献，但鲜为人知。本文描述的强大方法的两种主要技术都可以追溯到LudwigFöppl。1941年，L。Föppl发表了一种在任意轴对称载荷作用下确定弹性变形的方法。重要的是，该公式的两个关键方程式具有允许简单反演的形式，因此为任意轴对称冲头提供了接触问题的完整解决方案。这种反演是在舒伯特论文中，在福珀尔教授的指导下进行的。

卡尔·路德维希·福普[ 1 ]当时是慕尼黑工业大学（现为慕尼黑工业大学）的力学教授。这把椅子的历史与几位著名的科学家有关：第一位持有者是约翰·鲍辛格[ 2 ]，其次是奥古斯特·奥托·弗普尔[ 3 ] –路德维希·弗普尔的父亲。1922年，路德维希·福珀（LudwigFöppl）被任命为第三位主席，随后是海因茨·诺伯（Heinz Neuber）[ 4 ]，霍斯特·利普曼（Horst Lippmann）[ 5 ]和埃瓦尔德·沃纳（EwaldWerner）（现任主席）。目前，椅子已更名：材料科学与材料力学研究所LehrstuhlfürWerkstoffkunde和Werkstoffmechanik。

路德维希·福佩尔（LudwigFöppl）与ZAMM有着密切的关系-担任编辑委员会成员，并撰写了多篇有关连续力学，结构力学，接触力学和光弹性的论文。值得一提的是，在ZAMM一百年的历史中，只有一次是由他的儿子（路德维希·福佩尔（LudwigFöppl）从1924）图1。

舒伯特（G. Schubert）在“ Ingenieur-Archiv”（今天的应用力学档案馆）中发表了上述论文的缩略版。R. Grammel于1929年（1929年12月首次发行）创办了这本著名且发展良好的期刊。与ZAMM的重点在于数学和力学的相互作用相反，“ Ingenieur-Archiv”致力于力学与机械和土木工程之间的相互作用。舒伯特（G. Schubert）的论文发表于1942年，与当时的ZAMM论文一样遭遇命运：由于德国的政治局势，只有少数研究人员研究了德国研究机构出版并用德语撰写的出版物。

由于舒伯特（Schubert）的论文对Föppl提出的方法进行了最佳概述，因此E. Popova和VL Popov的论文主要致力于该论文，并且还包含其完整的英文翻译版本。