Characterization of the Quasi-static Deformation of LAAG Joints Adhering Machined Steel Surfaces

2005 ◽  
Vol 127 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Edward C. De Meter
Keyword(s):  
Static Loading ◽  
Steel Surface ◽  
Failure Modes ◽  
Axial Loading ◽  
Adhesive Bond ◽  
Shear Loading ◽  
Adhesive Joints ◽  
On Demand ◽  
Steel Surfaces

Light Activated Adhesive Gripper (LAAG) workholding technology is a means by which a workpiece is held by adhesive joints that can be instantaneously cured or destroyed, on demand. A LAAG joint is the adhesive bond between the gripper pin and workpiece. Due to the novelty of this concept, no knowledge exists with regard to how LAAG joints deform and fail during quasi-static loading. This paper describes an investigation that was carried out to characterize the strength, ductility, and failure modes of a LAAG joint adhering a machined, steel surface subject to axial loading and shear loading.

An Experimental Study on the Shear Strength of Steel Structures Joints

2012 ◽  
Vol 268-270 ◽  
pp. 279-282
Author(s):  
Piero Morelli
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Failure Modes ◽  
Axial Loading ◽  
Steel Structures ◽  
Shear Loading ◽  
Testing Device ◽  
Static Loads ◽  
Structural Joints ◽  
Structure Collapse

The results of an experimental investigation on the shear strength of structural joints are presented and discussed. Joint typologies generally employed in structural frames of industrial warehouses and intermediate floors are taken into consideration. Specimens were supplied by an industrial shelving manufacturer, in two different configurations: the first one characterized by steel pressed geometrical connectors and the second one consisting in bolted fittings to angular welded supporting plates. A specific testing device has been designed in order to transfer axial loading into shear loading applied to a couple of joints in a symmetrical testing configuration. Quasi-static loads were applied with increasingly intensity steps, until the yielding of the material or the overall structure collapse were reached. Failure modes of the tested joints are analyzed and discussed.

A Study on Evaluation of Impact Strength of Adhesive Joints Subjected to Impact Shear Loadings

2008 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Toshimasa Nagai ◽  
Takeshi Iwamoto ◽  
Hideaki Kuramoto
Keyword(s):  
Impact Strength ◽  
Adhesive Joint ◽  
Static Loading ◽  
Split Hopkinson Pressure Bar ◽  
Shear Loading ◽  
Adhesive Joints ◽  
Stress Distributions ◽  
Adhesive Thickness ◽  
The Impact ◽  
Strength Of Adhesive Joints

Adhesive joints in mechanical structures are subjected to static loading as well as impact loading. It is desired for the adhesive joints to have sufficient strength under both static and impact loadings. A lot of studies on the adhesive joints and the joint strength subjected to static loading have been carried out and examined. A few research works on the adhesive joint subjected to dynamic loading have been done, however, it has not fully elucidated for applying the joints to important sections in mechanical structures. In this study, the impact strength of adhesive joints subjected to impact shear loading is investigated using modified split Hopkinson pressure bar (SHPB) apparatus. The shear strength of adhesive joint, in which a solid cylinder is bonded to a hollow cylinder by an adhesive, is determined from maximum applied shear stress. A commercial thermosetting epoxy adhesive is used in the experiments. At the same time, the stress distributions in the joints subjected to impact shear loading are simulated by the finite-element analyses (FEA). The effect of adhesive thickness is investigated experimentally and computationally. It is shown that the strength is greatly affected by the adhesive thickness and the effect on the stress distributions in the joint is discussed.

Face/Core Debonding Characterization of Foam and Honeycomb Core Sandwich Structures Using Single Cantilever Beam Testing Method

2017 ◽  
Author(s):  
Mohammad Tauhiduzzaman ◽  
Seyed Morteza Sabet ◽  
Leif A. Carlsson
Keyword(s):  
Fracture Toughness ◽  
Cantilever Beam ◽  
Failure Modes ◽  
Beam Theory ◽  
Shear Loading ◽  
Least Square ◽  
Honeycomb Core ◽  
Precracked Specimen ◽  
Scb Test

Single Cantilever Beam (SCB) testing was conducted on foam and honeycomb core sandwich specimens to predict the fracture toughness and bonding strength. Adhesion characteristics can also be identified between facesheet and core materials conducting SCB test on precracked specimen. Disbonding under combined tensile and shear loading may involve failure modes such as kinking and cell buckling. Modified Beam Theory (MBT) method specifies required parameters to generate a least square plot based on experimentally determined compliance and disbond length obtained during the SCB test. Interfacial fracture toughness Gc, enumerated by following recommended data reduction methodologies, required to predict minimum Gc to initiate disbond growth. Finally, experimental compliance was compared with elastic foundation stiffness compliance to verify the performance of the test. Good agreement between two compliance solutions validates the accuracy of the SCB test.

Effect of Loading Conditions on Deformation and Failure of Composite Sandwich Structures

2001 ◽  
Author(s):  
Isaac M. Daniel ◽  
Emmanuel E. Gdoutos ◽  
Jandro L. Abot ◽  
Kuang-An Wang
Keyword(s):  
Failure Modes ◽  
Axial Loading ◽  
Bending Moment ◽  
Adhesive Bond ◽  
Failure Criteria ◽  
The State ◽  
Deformation And Failure ◽  
Composite Sandwich ◽  
State Of Stress ◽  
Aluminum Honeycomb

Abstract An investigation was conducted of failure modes and criteria for their occurrence in composite sandwich columns and beams. The initiation of the various failure modes depends on the material properties of the constituents (facings and core), geometric dimensions and type of loading. The loading type or condition determines the state of stress throughout the sandwich structure, which controls the location and mode of failure. The appropriate failure criteria at any point of the structure account for the biaxiality or triaxiality of the state of stress. The specimens were made of unidirectional carbon/epoxy facings and aluminum honeycomb and PVC closed-cell foam cores. The constituent materials were fully characterized and, in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Sandwich specimens were loaded under bending moment, shear and axial loading and failure modes were observed and compared with analytical predictions. The failure modes investigated are face sheet compressive failure, adhesive bond failure, indentation failure, core failure and facing wrinkling. The transition from one failure mode to another for varying loading or state of stress was discussed. Experimental results were compared with analytical predictions.

Selection substantiation of mechanical treatment method of machine part surfaces to be glued with metal-filled adhesive compounds

2021 ◽  
Vol 0 (7) ◽  
pp. 30-35
Author(s):  
E. A. Kosenko ◽  
◽  
R. I. Nigmetzyanov ◽  
V. V. Kostrykin ◽  
◽  
...  
Keyword(s):  
Machine Part ◽  
Mechanical Treatment ◽  
Shear Test ◽  
Adhesive Bond ◽  
Treatment Method ◽  
Adhesive Joints ◽  
Test Results ◽  
Adhesive Compound ◽  
Steel Surfaces ◽  
Steel Substrates

In production and repair of mechanical engineering products, poor preparation of surfaces for gluing leads to a decrease in adhesion or even to the destruction of the adhesive bond. The level of strength of the adhesive bond is determined not only by the absence of contamination on the surfaces to be bonded, but also largely depends on the type of materials to be bonded, the properties of the adhesive used and the geometric parameters of the surface. The analysis results of the quality and roughness of aluminum and steel surfaces obtained by various methods of machining are discussed. The shear test results for adhesive joints are presented. The tests were carried out on adhesive joints of aluminum and steel substrates, the surfaces of which were treated with sanding belts with grit sizes P40, P80 and P120 before gluing. A metal-filled adhesive compound based on epoxy resin with the addition of 3% aluminum powder (by weight) was used as the glue. The character of destruction of the studied adhesive joints is described. Recommendations on method srelection for machining aluminum and steel materials before gluing are presented.

Experimental Damage Characterization of Hexagonal Honeycombs Subjected to In-Plane Shear Loading

2010 ◽  
Author(s):  
Shraddha Joshi ◽  
Jaehyung Ju ◽  
Luke Berglind ◽  
Roy Rusly ◽  
Joshua D. Summers ◽  
...  
Keyword(s):  
Cell Wall ◽  
Wall Thickness ◽  
Failure Modes ◽  
Shear Loading ◽  
Cell Wall Thickness ◽  
Plane Shear ◽  
Post Buckling ◽  
Proper Design ◽  
Local Cell

Experimental study on the damage of hexagonal honeycombs under in–plane shear loading does not appear to be available in the literature. In this paper, shear damage behaviors of five different hexagonal mesostructures are investigated with rapid prototyped polycarbonate (PC) honeycomb coupon samples and proper design of a fixture for shear loading. Effective shear stress-strain curves of PC honeycomb coupons are generated for each shear test and the corresponding local cell wall failure is investigated. Two different failure modes of PC honeycombs were observed primarily depending on the cell wall thickness: The PC honeycombs having a lower cell wall thickness induce the plastic post buckling, resulting in preventing propagation of initial cracks through the cell wall end up with higher plastic load bearing. On the other hand, the failure mode of the honeycombs having a high cell wall thickness is the cell wall fracture by crack propagation through wall without severe buckling.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Electrical Characterization of Different Failure Modes in Sub-100 nm Devices Using Nanoprobing Technique

2009 ◽  
Author(s):  
E. Hendarto ◽  
S.L. Toh ◽  
J. Sudijono ◽  
P.K. Tan ◽  
H. Tan ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Focused Ion Beam ◽  
Failure Modes ◽  
Ion Beam ◽  
Electrical Characterization ◽  
Nickel Silicide ◽  
Fault Isolation ◽  
Technology Nodes ◽  
Scanning Electron

Abstract The scanning electron microscope (SEM) based nanoprobing technique has established itself as an indispensable failure analysis (FA) technique as technology nodes continue to shrink according to Moore's Law. Although it has its share of disadvantages, SEM-based nanoprobing is often preferred because of its advantages over other FA techniques such as focused ion beam in fault isolation. This paper presents the effectiveness of the nanoprobing technique in isolating nanoscale defects in three different cases in sub-100 nm devices: soft-fail defect caused by asymmetrical nickel silicide (NiSi) formation, hard-fail defect caused by abnormal NiSi formation leading to contact-poly short, and isolation of resistive contact in a large electrical test structure. Results suggest that the SEM based nanoprobing technique is particularly useful in identifying causes of soft-fails and plays a very important role in investigating the cause of hard-fails and improving device yield.

Case Study and Fault Modeling for Wrong Redundancy Evaluation on DRAM Devices

2007 ◽  
Author(s):  
Martin Versen ◽  
Dorina Diaconescu ◽  
Jerome Touzel
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Fault Modeling ◽  
Mode Analysis ◽  
Root Cause ◽  
Failure Mode Analysis

Abstract The characterization of failure modes of DRAM is often straight forward if array related hard failures with specific addresses for localization are concerned. The paper presents a case study of a bitline oriented failure mode connected to a redundancy evaluation in the DRAM periphery. The failure mode analysis and fault modeling focus both on the root-cause and on the test aspects of the problem.

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