Static and Impact Behavior of Self-Pierced Rivet Connections in Aluminum

2001 ◽  
Author(s):  
Chelliah Madasamy ◽  
Omar Faruque ◽  
Tau Tyan ◽  
Robert Thomas
Keyword(s):  
Strain Rate ◽  
Design Process ◽  
Failure Modes ◽  
Shear Loading ◽  
Peak Force ◽  
Impact Behavior ◽  
Impact Performance ◽  
Lap Shear ◽  
Shear Modes ◽  
Importance Assessment

Abstract Self-pierced riveted (SPR) connections in aluminum coupons were tested to evaluate their static and impact performance for automotive vehicle applications. The variables studied included: top gage, bottom gage, rivet size, adhesive, pre-strain, rivet location, strain-rate, and temperature. The SPR connections were tested for coach peel, u-tension, and lap shear modes. A variable importance assessment as well as the estimated effect of the variables on peak force and energy absorption was determined. The failure modes observed during testing were consistent. From this study, it was found that the top gage, bottom gage, and temperature were very sensitive for coach peel, u-tension, and lap shear. Additionally, adhesive was found to be important for shear loading, strain-rate increased the peak force when adhesive was present and, rivet size had a significant effect on both u-tension and coach peel modes. The effect of pre-strain and rivet location was minimal, and therefore their effect in the design process can be considered minimal.

scholarly journals Strain Rate Dependent Behavior of Vinyl Nitrile Helmet Foam in Compression and Combined Compression and Shear

2020 ◽  
Vol 10 (22) ◽  
pp. 8286
Author(s):  
Nicolas Bailly ◽  
Yvan Petit ◽  
Jean-Michel Desrosier ◽  
Olivier Laperriere ◽  
Simon Langlois ◽  
...  
Keyword(s):  
Strain Rate ◽  
Shear Loading ◽  
Combined Loading ◽  
Impact Behavior ◽  
Rate Variation ◽  
Shear Stresses ◽  
Absorbed Energy ◽  
Static Compression ◽  
Rate Dependent ◽  
Dependent Behavior

Vinyl nitrile foams are polymeric closed-cell foam commonly used for energy absorption in helmets. However, their impact behavior has never been described in isolation. This study aims to characterize the strain rate dependent behavior of three VN foams in compression and combined compression and shear. Vinyl nitrile samples of density 97.5, 125, and 183 kg/m3 were submitted to quasi-static compression (0.01 s−1) and impacts in compression and combined compression and shear (loading direction of 45°). For impacts, a drop test rig was used, and a method was developed to account for strain rate variation during impactor deceleration. Young’s modulus and stress at plateau were correlated with foam density in both compression and combined loading. Vinyl nitrile foams were strain rate dependent: The absorbed energy at the onset of densification was two to four times higher at 100 s−1 than at 0.01 s−1. In combined loading, the compressive stress at yield was reduced by 43% at a high strain rate. Compared to expanded polypropylene, vinyl nitrile foams transmitted less stress at the onset of densification for equivalent absorbed energy and presented a larger ratio between the compression and shear stresses in combined loading (0.37 at yield). This larger ratio between the compression and shear stresses might explain why vinyl nitrile helmet liners are thought to be better at reducing head rotational acceleration than expanded polypropylene helmet liners.

scholarly journals Evaluation of Single-Lap and Block Shear Test Methods in Adhesively Bonded Composite Joints

2021 ◽  
Vol 5 (1) ◽  
pp. 27
Author(s):  
Alec Redmann ◽  
Vinay Damodaran ◽  
Felix Tischer ◽  
Pavana Prabhakar ◽  
Tim A. Osswald
Keyword(s):  
Composite Structures ◽  
Joint Strength ◽  
Adhesive Bonding ◽  
Failure Modes ◽  
Shear Loading ◽  
Analytical Models ◽  
Normal Stresses ◽  
Block Shear ◽  
Lap Shear ◽  
Shear Joint

Adhesive bonding is increasingly being used for composite structures, especially in aerospace and automotive industries. One common joint configuration used to test adhesive strength is the single-lap shear joint, which has been widely studied and shown to produce significant normal (peeling) stresses. When bonding composite structures, the normal stresses are capable of causing delamination before the adhesive bond fails, providing inconclusive engineering data regarding the bonding strength. An alternative test is the block shear joint, which uses a shorter sample geometry and a compressive-shear loading to reduce normal stresses. Analytical models proposed by Goland and Reissner and Hart-Smith are used to compare the edge-bending moment for the two joint configurations. The stress distributions along the bondline are also compared using finite element analysis. Experimental tests are conducted to evaluate these analyses and the failure modes of each configuration are recorded. Block shear samples demonstrate a joint strength over 100% higher than single-lap shear specimen bonded with the same adhesive material. The lower joint strength measured in single-lap shear is found to be potentially misleading due to delamination of the composite adherend.

Sensor Fusion and On-Line Monitoring of Friction Stir Blind Riveting for Lightweight Materials Manufacturing

2021 ◽  
pp. 1-36
Author(s):  
Zhe Gao ◽  
Haris Khan ◽  
Jingjing Li ◽  
Weihong Guo
Keyword(s):  
Sensor Fusion ◽  
Failure Modes ◽  
Processing Parameters ◽  
Data Driven ◽  
Structure Property ◽  
Cross Sectional ◽  
Friction Stir ◽  
In Situ Data ◽  
Lap Shear

Abstract This research focused on developing a hybrid quality monitoring model through combining the data driven and key engineering parameters to predict the friction stir blind riveting (FSBR) joint quality. The hybrid model was formulated through utilizing the in-situ processing and joint property data. The in-situ data involved sensor fusion (force and torque signals) and key processing parameters (spindle speed, feed rate and stacking sequence) for data-driven modeling. The quality of the FSBR joints was defined by the tensile strength. Further, the joint cross-sectional analysis and failure modes in lap-shear tests were employed to confirm the efficacy of the proposed model and development of the process-structure-property relationship.

scholarly journals Strain rate and thermal softening effects in shear testing of AA7075-T6 sheet

2018 ◽  
Vol 183 ◽  
pp. 02037 ◽  
Author(s):  
Taamjeed Rahmaan ◽  
Ping Zhou ◽  
Cliff Butcher ◽  
Michael J. Worswick
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Rate Sensitivity ◽  
Thermal Conditions ◽  
Shear Loading ◽  
Image Correlation ◽  
High Rate ◽  
Strain Rates ◽  
Shear Testing ◽  
Plane Shear

Shear tests were performed at strain rates ranging from quasi-static (0.01 s-1) to 500 s-1 for AA7075-T6 sheet metal alloy at room temperature. A miniature sized shear specimen was used in this work to perform high strain rate shear testing. Digital image correlation (DIC) techniques were employed to measure the strains in the experiments. At maximum in-plane shear strains greater than 20%, the AA7075-T6 alloy demonstrated a reduced work hardening rate at elevated strain rates. At lower strains, the AA7075-T6 alloy showed mild positive rate sensitivity. The strain to localization (using the Zener-Holloman criterion), measured using the DIC technique, decreased with strain rate in shear loading. The strain at complete failure, however, exhibited an increase at the highest strain rate (500 s-1). The current work also focused on characterization of the thermal conditions occurring during high rate loading in shear with in situ high speed thermal imaging. Experimental results from the highest strain rate (500 s-1) tests showed a notable increase in temperature within the specimen gauge region as a result of the conversion of plastic deformation energy into heat.

In-Situ Continuous Process for Bonding Glass-Fiber Reinforced Polypropylene to Wood

1999 ◽  
Author(s):  
Karthik Ramani ◽  
Michael Smith ◽  
Heming Dai
Keyword(s):  
Failure Modes ◽  
Continuous Process ◽  
Heating Time ◽  
Bond Line ◽  
Process Conditions ◽  
Processing Times ◽  
Lap Shear ◽  
Glass Fiber Reinforced ◽  
Anisotropic Fiber

Abstract Process conditions are developed for the manufacture of composite reinforcement for oak. Commingled glass and polypropylene fibers are consolidated in-situ on the surface of oak. Processing times from 30 to 120 seconds and pressures from .34 MPa to 1.4 MPa are tested. Micrographs of the composite and bond line reveal anisotropic fiber distribution in the composite, dry reinforcing fibers, voids, and incomplete consolidation. These microstructures are correlated with the processing problems which cause them, including insufficient heating time, poor matrix/glass mixing, and insufficient pressure to suppress void development. Lap shear strength and failure modes are related to microstructural features.

Effect of stirring time on the mechanical behavior of friction stir spot weld of Al 6061-T6 lap-shear configuration

2018 ◽  
Vol 233 (10) ◽  
pp. 3583-3591 ◽  
Author(s):  
Amirreza Shahani ◽  
Ali Farrahi
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Static Strength ◽  
High Load ◽  
Welding Condition ◽  
Friction Stir ◽  
Al 6061 ◽  
Lap Shear ◽  
Low Load ◽  
Stirring Time

The effect of five different stirring times of friction stir spot welding on lap-shear specimens of Al 6061-T6 alloy has been experimentally analyzed. The welding condition with 2 s of stirring shows the optimum mechanical behavior in comparison to the others. The static strength and fatigue behavior of the joint are justified using the microhardness profiles. The static results prove that the increase of stirring time beyond the 2 s case has little effect on improving the static strength. The fatigue results reveal two different failure modes, which are shear fracture at high load levels and transverse crack growth at low load levels. At medium load levels, although the final failure is similar to high load levels, the transverse growth of the crack outside the welding zone, just like low load levels, is also observed.

Bond Behaviour of FRCM Composites: Effects of High Temperature

2019 ◽  
Vol 817 ◽  
pp. 161-166
Author(s):  
Antonio Iorfida ◽  
Sebastiano Candamano ◽  
Fortunato Crea ◽  
Luciano Ombres ◽  
Salvatore Verre ◽  
...  
Keyword(s):  
High Temperature ◽  
Failure Mode ◽  
Failure Modes ◽  
Construction Materials ◽  
Mechanical Damage ◽  
High Density ◽  
Bond Behaviour ◽  
Bond Slip ◽  
Masonry Construction ◽  
Lap Shear

The fire remains one of the serious potential risks to most buildings and structures, as recently it’s been witnessed in Paris’ historic Notre Dame Cathedral and London’s Grenfell Tower. Concrete and masonry construction materials suffer physiochemical changes and mechanical damage caused by heating that is usually confined to the outer surface but can eventually compromise their load-bearing capacity. FRCM systems could provide when applied, supplemental fire insulation on pre-existing structural members, but there is a lack of knowledge about their properties in those conditions. This experimental work, thus, aims to evaluate the mechanical behaviour of carbon-FRCM and basalt-FRCM composites bonded to masonry substrate after high temperature exposure. Temperatures of 100 °C, 300 °C and 500 °C over a period of three hours were used to investigate the degradation of their mechanical properties. Single lap shear bond tests were carried out to evaluate the bond-slip response and failure modes. For all the tested temperatures higher peak stresses were measured for carbon-FRCM composite than basalt ones. Furthermore, low-density basalt-FRCM composite showed higher peak stresses and lower global slips up to 300 °C than high-density one. Carbon-FRCM composite failure mode was not effected by temperature. High-density basalt-FRCM composite showed a change in failure mode between 300 °C and 500 °C.

Local FRP-Reinforcement of Clay Hollow Block Panels under Shear Loading

2019 ◽  
Vol 817 ◽  
pp. 450-457
Author(s):  
Antonio Borri ◽  
Marco Corradi ◽  
Romina Sisti ◽  
Alessio Molinari ◽  
Chiara Quintaliani
Keyword(s):  
Failure Modes ◽  
Load Capacity ◽  
Shear Loading ◽  
Test Results ◽  
Lateral Capacity ◽  
Viable Solution ◽  
Splitting Failure ◽  
Masonry Material ◽  
Frp Reinforcement ◽  
Hollow Block

The use of clay hollow blocks is common for new constructions in many parts of Europe. The results of 8 full-scale shear tests of block-masonry panels (dimensions 1.60x0.90x0.25 m) are reported in this paper. Non-defective and defective wall panels were tested in shear in the laboratory. Typical failure modes are investigated, not previously reported in the scientific literature. Test results show that the lateral load capacity of the panels is highly affected by construction defects. Furthermore, CFRPs were used in this research as local reinforcement (repair) in the area around the cracks previously opened in the masonry material. The lateral capacity for CFRP-repaired panels was restored to the original value of non-defective panels, indicating that the CFRP-repair of cracked panels is viable solution. An explanation for this phenomenon is suggested, which indicates that the high tensile strength of CFRPs can be effective in repairing cracked block-masonry. It is also argued that this large stress level of the CFRPs leads to a premature tensile CFRP crisis or a splitting failure of the blocks’ shells.

Experimental investigation and modeling of dynamic thermomechanical behavior of 4-harness satin weave carbon/epoxy composites

2017 ◽  
Vol 31 (9) ◽  
pp. 1181-1203 ◽  
Author(s):  
Xueyao Hu ◽  
Hui Guo ◽  
Weiguo Guo ◽  
Feng Xu ◽  
Longyang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Composite Laminates ◽  
Failure Modes ◽  
Shear Failure ◽  
Experimental Studies ◽  
Temperature Shift ◽  
Thermomechanical Coupling ◽  
Longitudinal Splitting ◽  
Wide Range

Theoretical and experimental studies on the compressive mechanical behavior of 4-harness satin weave carbon/epoxy composite laminates under in-plane loading are conducted over the temperature range of 298–473 K and the strain rate range of 0.001–1700/s in this article. The stress–strain curves of 4-harness satin weave composites are obtained at different strain rates and temperatures, and key mechanical properties of the material are determined. The deformation mechanism and failure morphology of the samples are observed and analyzed by scanning electron microscope (SEM) micrographs. The results show that the uniaxial compressive mechanical properties of 4-harness satin weave composites are strongly dependent on the temperature but are weakly sensitive to strain rate. The peak stress and elastic modulus of the material have the trend of decrease with the increasing of temperature, and the decreasing trend can be expressed as the functional relationship of temperature shift factor. In addition, SEM observations show that the quasi-static failure mode of 4-harness satin weave composites is shear failure along the diagonal lines of the specimens, while the dynamic failure modes of the material are multiple delaminations and longitudinal splitting, and with the increasing of temperature, its longitudinal splitting is more serious, but the delamination is relatively reduced. A constitutive model with thermomechanical coupling effects is proposed based on the experimental results and the increment theory of elastic–plastic mechanics. The experimental verification and numerical analysis show that the model is shown to be able to predict the finite deformation behavior of 4-harness satin weave composites over a wide range of temperatures.

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