Failure Mechanisms of Weld Bonded Lap Joints Between Composite/Metal Adherends

2014 ◽  
Author(s):  
Lijun Li ◽  
Lingyu Sun
Keyword(s):  
Failure Mode ◽  
Adhesive Bonding ◽  
Failure Modes ◽  
Load Transfer ◽  
Engineering Application ◽  
Element Model ◽  
Simulation Method ◽  
Lap Joints ◽  
Transfer Path ◽  
The Impact

Weld-bonding, a combination of spot welding and adhesive bonding, is a primary method of joining the composite underbody to the steel body-in-white (BIW). This concept is provided by the Automotive Composites Consortium (ACC) to ensure the compatibility with the OEM assembly processes. This paper established the finite element model of the weld bonded lap joint based on the published specimen dimensions, and compared the ultimate load and failure mode with their experimental results. Their good agreements demonstrated the accuracy of the numerical model and simulation method. Using this model, the progressive failures within the joints were predicted under static tensile loading and impact loading, respectively. The impact resistant capability of this joint was evaluated and the load transfer path among the adhesives, welded spot, composite and HSS adherend was discussed. The influences of relative thickness and relative stiffness between the adhesives and the two adherends on the failure modes were studied numerically, and the map chart for failure mode prediction was provided for weld bonded lap joints of bi-materials adherends, which is helpful for engineering application.

Effect of Autoclave Cure Time and Surface Preparation on Film Adhesive Bond in Lightweight Material Joints

2018 ◽  
Author(s):  
Isotta Morfini ◽  
Luca Goglio ◽  
Giovanni Belingardi ◽  
Sayed A. Nassar
Keyword(s):  
Failure Mode ◽  
Load Transfer ◽  
Mechanical Performance ◽  
Surface Preparation ◽  
Adhesive Bond ◽  
Lap Joints ◽  
Mode Analysis ◽  
Bonding Parameters ◽  
Film Adhesive ◽  
Cure Time

This study investigates the effect of cure time and surface roughness on mechanical performance of single lap joints (SLJ). Test joints are made of aluminum/aluminum or aluminum/magnesium adherends that are autoclave-bonded using a commercially available film adhesive. Joint mechanical performance is assessed in terms of the static load transfer capacity (LTC), fatigue life and failure mode. Except for the cure time, all the rates of the other autoclave-bonding parameters are kept constant; namely, the level of cure temperature and pressure, as well as the rates of autoclave heating, cooling, pressurization and depressurization. Test data, failure mode analysis, discussion, observations and conclusions are provided.

Optimal Reliability and Cost of Non-Repairable Systems Subject to Two Failure Modes Considering Correlated Failures

2018 ◽  
Vol 25 (05) ◽  
pp. 1850024
Author(s):  
Anusha Krishna Murthy ◽  
Saikath Bhattacharya ◽  
Lance Fiondella
Keyword(s):  
Failure Mode ◽  
System Reliability ◽  
Failure Modes ◽  
Optimal Number ◽  
Optimal Designs ◽  
Repairable Systems ◽  
Independent Manner ◽  
Reliability Models ◽  
Correlated Failures ◽  
The Impact

Most reliability models assume that components and systems experience one failure mode. Several systems such as hardware, however, are prone to more than one mode of failure. Past two-failure mode research derives equations to maximize reliability or minimize cost by identifying the optimal number of components. However, many if not all of these equations are derived from models that make the simplifying assumption that components fail in a statistically independent manner. In this paper, models to assess the impact of correlation on two-failure mode system reliability and cost are developed and corresponding expressions for reliability and cost optimal designs derived. Our illustrations demonstrate that, despite correlation, the approach identifies reliability and cost optimal designs.

Experimental investigation on adhesive bonding of similar and dissimilar weld joint used for automotive applications

2021 ◽  
pp. 095440892110631
Author(s):  
Rohit Verma ◽  
Lochan Sharma ◽  
Mayank Chauhan ◽  
Rahul Chhibber ◽  
Kanwer Singh Arora
Keyword(s):  
Tensile Strength ◽  
Failure Mode ◽  
Adhesive Bonding ◽  
Lap Joints ◽  
Mode Analysis ◽  
Dissimilar Joints ◽  
Bonding Parameters ◽  
Adhesion Failure ◽  
Failure Mode Analysis ◽  
Length Changes

The automobile industry has started using adhesive bonding to join load bearing components which aerospace industry has been using for decades. Adhesive lap joints are used frequently in the manufacture of automobile. In present study, structural adhesives were used to join the aluminium alloy (AA5083 H111) with the HSS dual phase (DP780) steel. Adhesive bonding appears to be one of the appropriate methods of joining dissimilar materials. The aim of this work is to analyze the tensile strength of similar and dissimilar joints. The influence of various parameters was also investigated such as the overlap length and the bondline thickness of specimens. In DP steel, there is 22% increase in strength for similar lap joint when overlap length changes from 10 mm to 15 mm, while there is 45% increase in strength when it varies from 15 mm to 20 mm. Similarly in case of Al alloy, there is 26% increased strength for similar lap joints when length varies from 10 mm to 15 mm, while it increased to 42% when length changes from 15 mm to 25 mm and there is about 35% increase in strength for length varies from 20 mm to 25 mm. In case of dissimilar joints, firstly there is about 16% increase in strength then there is 5% decrease while after that there is 45% increase in strength. Adhesion failure, cohesion failure and mixed failure were obtained experimentally during failure mode analysis. As the strength of joint increases, failure mode shows a transition from adhesion failure to cohesion failure. From the literature survey it is evident that limited work has been carried out on analysis of shear-tensile strength of adhesively bonded steel and aluminium joint with variation in bonding parameters. Not much work on failure mode analysis of bonded joints during tensile testing has been reported. In present work a noval attempt has been made to analyze the shear-tensile strength and failure mode of adhesively bonded steel and aluminium joint with variation in bonding parameters.

Experimental and numerical study of the dynamic response of an adhesively bonded automotive structure

2020 ◽  
Vol 234 (14) ◽  
pp. 3385-3397
Author(s):  
NDD Silva ◽  
JJM Machado ◽  
EAS Marques ◽  
PMGP Moreira ◽  
LFM da Silva
Keyword(s):  
Adhesive Bonding ◽  
Numerical Study ◽  
Low Cost ◽  
High Strength ◽  
Epoxy Adhesive ◽  
Lap Joints ◽  
Impact Response ◽  
Vehicle Body ◽  
Component Level ◽  
The Impact

Based on economic and environmental factors related to energy efficiency, the automotive industry is being increasingly encouraged to design lighter structures, making use of adhesive bonding in vehicle body frames. To meet the standards of the automotive sector, adhesive joints must provide high strength and stiffness, low cost and good energy absorption at a component level, thereby ensuring good impact strength and passenger safety. This work aims to study, at room temperature (24°C), the impact response of a real scale automotive structure bonded with a crash-resistant epoxy, allowing to access the suitability of adhesives for automotive structural purposes. The epoxy adhesive was found to successfully transfer the loads to the aluminium substrates and not to compromise the integrity of the structure, as its failure was dominated by the behaviour of aluminium. Results obtained with a numerical model of the component were found to be in close agreement with the experimental failure load, demonstrating that numerical analysis can be a viable tool to predict the structure’s behaviour. In addition, a polyurethane was used as an alternative to the epoxy system to bond the structure, proving that the joint behaves better in the presence of a more flexible adhesive, as no failure was found for this case. Aluminium single-lap joints with two adhesive thicknesses were tested as a complement to understand the influence of this parameter on the impact response of a joint, showing a 21% decrease in strength when the highest thickness was used.

Experimental Investigation on Adhesive Bonded Joints of Carbon Fiber Composite Laminates Containing Disbond Defect

2017 ◽  
Author(s):  
Ping Qiu ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Carbon Fiber ◽  
Adhesive Bonding ◽  
Phased Array ◽  
Failure Modes ◽  
Fiber Composite ◽  
Failure Process ◽  
Tensile Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Image Correlation

Adhesive bonding technology is widely used for connecting composite pipes recent years, for the adhesive joints have many advantages such as weight reduction, ease of manufacture, and more importantly, uniform stress distribution and less stress concentration within the joint region. Nevertheless, one of the limitations of adhesive joints is the difficulty in predicting the joint strength due to the presence of defects in the adhesive due to improper curing process. This paper presents an experimental study of single-lap joints with disbond defects at the adherend-adhesive interface. Different sets of adhesively-bonded singlelap joints containing varied disbond conditions were prepared and tested. The joints used carbon fiber reinforced polymer (CFRP) laminates as substrates and epoxy resin as adhesive, with ultrathin aluminum foil (10um) as disbond defects in different sizes and locations. The full deformation fields were measured using the digital image correlation (DIC) method. The samples were subjected to tensile load till failure to determine the bond strength. Before the tensile test, the defective adhesive joints were detected by a phased-array ultrasonic instrument to identify the bond-line quality of joints. The results show that the disbond defects can be detect by ultrasonic phased-array technique, and the detriment of disbond defect to the failure process can be observed and recorded by DIC system. Based on the findings, the failure modes and failure mechanism of bonded CFRP joint were further discussed.

Effect of Adhesive Nano-Additives on Static Load Transfer Capacity and Failure Mode of Bonded Steel-Magnesium Single Lap Joints

2015 ◽  
Author(s):  
Sayed A. Nassar ◽  
Kassem Moustafa ◽  
Zhijun Wu ◽  
Demetrios Tzelepis
Keyword(s):  
Failure Mode ◽  
Load Transfer ◽  
Lap Joints ◽  
Mode Analysis ◽  
Paper Test ◽  
Single Lap Joints ◽  
Nano Powder ◽  
Failure Mode Analysis ◽  
Particulate Size ◽  
20 Nm

An experimental procedure and test setup is used for investigating effect of using nanoparticle additives to the adhesive on the load transfer capacity (LTC) of bonded magnesium (Mg)-steel (St) single lap joints (SLJ). Investigated variables include the nano-powder material (Alumina vs. Silica), particulate size (20 nm vs. 80 nm), and concentration in the adhesive (2.5% wt. vs 5.0 % wt.). Two different levels of surface roughness on the bonded area are used; namely, sanding the bond area with G60 or G180 sand paper. Test data and SEM failure mode analysis are provided.

Approach for the Evaluation of the Impact of Potential Software Failures in Software-Based Instrumentation and Control (I&C) Equipment in Nuclear Power Plants

2016 ◽  
Author(s):  
Hervé Mbonjo ◽  
Manuela Jopen ◽  
Birte Ulrich ◽  
Dagmar Sommer
Keyword(s):  
Failure Mode ◽  
Nuclear Power ◽  
Power Plants ◽  
Failure Modes ◽  
Operating Experience ◽  
Generic Model ◽  
Software Failures ◽  
Software Failure ◽  
Potential Safety ◽  
The Impact

In this paper we present an approach for the evaluation and assessment of the impact of software failures in software-based I&C systems of NPPs. The proposed two-step approach includes at the first step the identification of software failure modes on the basis of review of operating experience gained with software-based I&C systems and equipment. All probable software failures in software-based I&C systems should be identified and classified according to e. g. the concerned system, the observed software failure mode and to their actual and potential safety relevance. In a second step an evaluation of the potential impact of identified safety relevant software failure modes in a software-based I&C system shall be performed. The evaluation shall be done by means of a failure mode and effects analysis (FMEA) using a generic model of the software-based I&C system, i.e. software failure modes are postulated in the I&C system and their potential safety-relevant impact is analyzed.

scholarly journals Nonlinear Finite Element Modelling of Railway Turnout System considering Bearer/Sleeper-Ballast Interaction

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
James Sae Siew ◽  
Olivia Mirza ◽  
Sakdirat Kaewunruen
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Load Transfer ◽  
Element Model ◽  
Operational Reliability ◽  
Fe Model ◽  
Rail Network ◽  
Numerical Studies ◽  
Frequent Monitoring ◽  
Great Consideration

Rail turnouts are built to enable flexibility in the rail network as they allow for vehicles to switch between various tracks, therefore maximizing the utilisation of existing rail infrastructure. In general, railway turnouts are a safety-critical and expensive feature to a rail system as they suffer aggressive operational loads, in comparison to a plain rail track, and thus require frequent monitoring and maintenance. In practice, great consideration is given to the dynamic interaction between the turnouts components as a failed component may have adverse effects on the performance of neighbouring components. This paper presents a nonlinear 3D finite element (FE) model, taking into account the nonlinearities of materials, in order to evaluate the interaction and behaviour of turnout components. Using ABAQUS, the finite element model was developed to simulate standard concrete bearers with 60 kg/m rail and with a tangential turnout radius of 250 m. The turnout structure is supported by a ballast layer, which is represented by a nonlinearly deformable tensionless solid. The numerical studies firstly demonstrate the importance of load transfer mechanisms in the failure modes of the turnout components. The outcome will lead to a better design and maintenance of railway turnouts, improving public safety and operational reliability.

Study of Failure Modes of Suction Anchors

2011 ◽  
Author(s):  
Qiyi Zhang ◽  
Sheng Dong
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Failure Mode ◽  
Failure Modes ◽  
Limit Equilibrium ◽  
Element Model ◽  
Ultimate Bearing Capacity ◽  
Engineering Practice ◽  
Element Analysis ◽  
Limit Equilibrium State

Suction foundations are widely used in deep sea and their ultimate bearing capacity which is closely related with failure modes of suction anchor at limit equilibrium state is a key technology in offshore engineering practice. Based on Coulomb friction theory, an exact finite element model is presented in this paper. On the basis of this FEM model, by use of the finite element analysis software ABAQUS, the effect of mooring point and aspect ratio of a suction anchor on the ultimate bearing capacity and its stability are researched in detail. The results show that the ultimate bearing capacity and stability of the suction anchor are affected vastly by the position of mooring point, and the variation of mooring point on the suction anchor can lead to different failure modes. Simultaneously, the results also shows that tilted rotation of the soil along the direction of the mooring force will occur when the mooring point is near the top of the suction anchor, and the soil near the bottom of the fixed anchor rotates around the center of a circle, so the failure mode is called forward-tilted rotation in this paper; A general translation slip of the soil in front of the anchor along the direction of the mooring force will occur when mooring point is below midpoint of suction anchor, so the failure mode is called the translation slip failure mode in this paper. Anticlockwise tilted rotation of the soil along the direction of mooting force will occur when the mooring point is near the bottom of the anchor, and the soil at the top of the anchor rotates around the center of a circle, so the failure mode is called backward-tilted rotation in this paper.

Ballistic performance and damage simulation of fiber metal laminates under high-velocity oblique impact

2020 ◽  
Vol 29 (7) ◽  
pp. 1011-1034 ◽  
Author(s):  
Chao Zhang ◽  
Qian Zhu ◽  
Jose L Curiel-Sosa ◽  
Tinh Quoc Bui
Keyword(s):  
Impact Velocity ◽  
High Velocity ◽  
Damage Mechanics ◽  
Failure Modes ◽  
Element Model ◽  
Oblique Impact ◽  
Ballistic Performance ◽  
Fiber Metal Laminates ◽  
Fiber Metal ◽  
The Impact

Fiber metal laminates have been successfully applied in military aircrafts, armor vehicles and other modern engineering industries as protective structures due to their outstanding impact resistant properties. Prediction of the ballistic performance and investigation on the damage mechanism of the fiber metal laminates under general oblique impact conditions still remain a very challenging issue. In this study, a nonlinear dynamic finite element model in terms of continuum damage mechanics including intra- and inter-layer failure modes is presented. The accuracy of this model is validated with available experimental data. The damage and ballistic performance of two different structural fiber metal laminates subjected to high-velocity oblique impact by rigid hemispherical nose projectile with angles of 0°, 30°, 45° and 60° are studied. The numerical results show that the projectile deflects when the oblique impact occurs and the deflection angle decreases with increasing the impact velocity. The residual velocity of the projectile and the energy absorption of the target are related to the initial impact velocity and impact angle of the projectile. The proposed simulation approach offers a new proper reference for numerical investigations of common oblique impact problems in other fiber metal laminates.

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