Samuel Tesfaye Molla, Assefa Asmare Tsegaw, Teshome Mulatie Bogale, Addisu Negash Ali, Asmamaw Tegegne Abebe

Tensile Strength of Adhesively Bonded Steel to Hybrid Sisal-Glass Reinforced HDPE Composite Joint for Automobile Side Body Panel Application

Introduction

Tensile strength of adhesively bonded steel to hybrid sisal-glass reinforced hdpe composite joint for automobile side body panel application. Investigates tensile strength of adhesively bonded steel to hybrid sisal-glass HDPE composites for automotive panels. Optimizes adhesive thickness for lightweight, sustainable solutions.

Abstract

The increasing demand for lightweight, high-performance, and environmentally sustainable materials in the automotive industry has accelerated the adoption of adhesive bonding as an alternative to conventional joining techniques such as welding and mechanical fastening. Reliable prediction of stress distribution and debonding behavior in adhesively bonded composite–metal joints is therefore essential to ensure structural integrity under service loading. This study presents a comprehensive computational and experimental investigation of the tensile stress behavior of adhesively bonded single-side strap joints (ABSSSJ) formed between steel and hybrid sisal–glass reinforced high-density polyethylene (HDPE) composites for automobile side body panel applications. The hybrid composite adherend was modeled as an orthotropic laminate with a ([0°/+45°/90°/–45°/0°]) stacking sequence, while the adhesive layer was characterized using different epoxy systems (Araldite 2020, Araldite 2015, and AV138) with thicknesses ranging from 0.12 to 1.0 mm and elastic moduli between 1.85 and 6 GPa. An analytical variational method was employed to evaluate shear and peel stress distributions, and the results were verified using a cohesive zone model (CZM)-based finite element approach to simulate crack initiation and progressive debonding. Experimental tensile and shear tests were conducted to validate the numerical predictions. The results indicate that an adhesive thickness of approximately 0.75 mm provides an optimal balance between load transfer efficiency and stress reduction at the overlap edges. The numerical and analytical predictions exhibited strong agreement with experimental measurements, with a maximum deviation below 6%. The validated results demonstrate that hybrid sisal–glass reinforced HDPE composites, when combined with appropriate adhesive and joint design, offer a promising, lightweight, and sustainable solution for automotive side body panel structures.

Review

This study addresses a critical need in the automotive industry for lightweight, high-performance, and environmentally sustainable materials by exploring the efficacy of adhesively bonded joints. Focusing on steel to hybrid sisal-glass reinforced high-density polyethylene (HDPE) composite joints, the research investigates their tensile strength behavior for potential application in automobile side body panels. The increasing shift from traditional joining methods to adhesive bonding, particularly for dissimilar material combinations like metal and composite, underscores the importance of accurately predicting stress distribution and debonding mechanisms. This paper offers a timely and relevant investigation into a promising material system that could significantly contribute to lightweighting initiatives and sustainable manufacturing in the automotive sector. The methodology employed in this research is commendably comprehensive, integrating analytical, computational, and experimental approaches. An analytical variational method was initially used to evaluate shear and peel stress distributions, subsequently verified through a cohesive zone model (CZM)-based finite element approach to simulate crack initiation and progressive debonding. The study systematically varied key parameters, including different epoxy adhesive systems (Araldite 2020, 2015, AV138), adhesive thicknesses ranging from 0.12 to 1.0 mm, and elastic moduli between 1.85 and 6 GPa, alongside an orthotropic composite laminate. A significant finding reveals an optimal adhesive thickness of approximately 0.75 mm, striking a crucial balance between efficient load transfer and stress reduction at the joint overlap edges. Crucially, the robust validation of numerical and analytical predictions against experimental tensile and shear tests, showing a maximum deviation below 6%, instills high confidence in the derived results. The paper's strengths lie in its multi-modal investigation, rigorous validation, and direct applicability to a pressing industrial challenge. By meticulously combining analytical modeling, advanced finite element simulations, and empirical testing, the authors provide a deep and credible understanding of the joint's mechanical behavior. The successful demonstration of hybrid sisal–glass reinforced HDPE composites, when optimally bonded to steel, as a promising, lightweight, and sustainable solution for automotive side body panels is a major contribution. This work not only offers valuable design guidelines for adhesively bonded composite-metal structures but also champions the use of more sustainable materials, paving the way for future advancements in automotive body panel design and manufacturing processes.

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