Elaboration of Design and Optimization Methods for a Newly Developed CFRP Sandwich-like Structure Validated by Experimental Measurements and Finite Element Analysis.

György Kovács

doi:10.3390/polym13244348

Abstract

Nowadays, the application of composite materials and light-weight structures is required in those industrial applications where the primary design aims are weight saving, high stiffness, corrosion resistance and vibration damping. The first goal of the study was to construct a new light-weight structure that utilizes the advantageous characteristics of Carbon Fiber Reinforced Plastic (CFRP) and Aluminum (Al) materials; furthermore, the properties of sandwich structures and cellular plates. Thus, the newly constructed structure has CFRP face sheets and Al stiffeners, which was manufactured in order to take experimental measurements. The second aim of the research was the elaboration of calculation methods for the middle deflection of the investigated sandwich-like structure and the stresses that occurred in the structural elements. The calculation methods were elaborated; furthermore, validated by experimental measurements and Finite Element analysis. The third main goal was the elaboration of a mass and cost optimization method for the investigated structure applying the Flexible Tolerance optimization method. During the optimization, seven design constraints were considered: total deflection; buckling of face sheets; web buckling in stiffeners; stress in face sheets; stress in stiffeners; eigenfrequency of the structure and constraints for the design variables. The main added values of the research are the elaboration of the calculation methods relating to the middle deflection and the occurred stresses; furthermore, elaboration of the optimization method. The primary aim of the optimization was the construction of the most light-weighted structure because the new light-weight sandwich-like structure can be utilized in many industrial applications, e.g., elements of vehicles (ship floors, airplane base-plate); transport containers; building constructions (building floors, bridge decks).

Highlights

The face sheets are riveted to the stiffeners
The main added value and novelty of the research are the following: (1) Calculation methods were elaborated on the one hand for the middle deflection of the newly constructed sandwich-like structure; on the other hand, for the stresses that occurred in the structural elements (CFRP face sheets and Al stiffeners)
Experimental tests were performed relating to the investigated new sandwich-like structure’s middle deflection and relating to the stresses that occurred in the structural elements of the structure (CFRP face sheets and Al stiffeners)

Summary

Introduction

Increasing market competition, fast changing customers’ demands and the pandemic situation results that companies have to put emphasis on the application of advanced materials, innovative structures and modern manufacturing technologies in order to maintain their competitiveness. FRP composites have many advantageous properties compared to metal materials, which are the following: low density, high strength, high vibration damping, chemical and corrosion resistance, high bending stiffness, good thermal insulation, advantageous design versatility, etc. [1,2].One of the most important characteristics of the FRP materials is their low density, which causes significant weight saving compared to traditional materials, such as steel.the FRP composites are widely used in those industrial applications where the primary design aim is weight saving, e.g., structural elements of transport vehicles; transport containers; chemical vessels; building constructions (building floors, elements of bridges or warehouses, etc.) [3,4,5].The fiber reinforced composite materials consist of two different components, which are the fibers and the basic matrix. The FRP composites are widely used in those industrial applications where the primary design aim is weight saving, e.g., structural elements of transport vehicles; transport containers; chemical vessels; building constructions (building floors, elements of bridges or warehouses, etc.) [3,4,5]. There are many types of fibers (e.g., carbon, glass, aramid) and matrix (e.g., resins, ceramics) materials. The combination of these components is infinite, which results in high variety of composite materials for several special engineering applications [6,7,8,9,10]

Objectives

Methods

Results

Conclusion