Investigations to increase the failure load for joints in glass epoxy composites

2018 ◽  
Vol 233 (6) ◽  
pp. 2074-2090 ◽  
Author(s):  
Kulwinder Singh ◽  
JS Saini ◽  
H Bhunia ◽  
Jaspreet Singh
Keyword(s):  
Failure Modes ◽  
Failure Load ◽  
Failure Criteria ◽  
Hole Diameter ◽  
Glass Fiber Reinforced ◽  
Failure Loads ◽  
Ultimate Failure ◽  
Nanoclay Content ◽  
Woven Glass Fiber ◽  
Fiber Reinforced Laminates

The present work aims to increase failure loads of pin joints through nanofillers and metal inserts. Pin joints were prepared from woven glass fiber-reinforced laminates with nanoclay as filler material along with metal inserts fitted in holes. To investigate the effect of nanoclay content, 1–5 wt.% of nanoclay was mixed in epoxy. The increase in tensile strength up to 3 wt.% of nanoclay was observed which was due to increase in the specific surface area of the nanocomposite material. Dispersed nanoclay filler particles act as mechanical interlocking between fiber and epoxy matrix which creates a high friction coefficient. The optimal nanoclay content of 3 wt.% was finally used to prepare nanocomposite laminates. The geometric parameters, i.e. edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio were varied from 2 to 5 and 3 to 6, respectively. Progressive damage analysis along with Hashin failure criteria was performed to predict failure loads and failure modes in pin joints, numerically. Metal inserts reduced the stress concentration around the hole and redistributed stresses at the pin/hole interface, which eventually increased the ultimate failure load of the joint.

Effect of Metallic Inserts on the Strength of Pin Joints Prepared from Glass Fiber Reinforced Composites

2017 ◽  
Vol 67 (5) ◽  
pp. 592 ◽  
Author(s):  
Kulwinder Singh ◽  
J. S. Saini ◽  
H. Bhunia
Keyword(s):  
Glass Fiber ◽  
Failure Modes ◽  
Failure Criteria ◽  
Hole Diameter ◽  
Progressive Damage ◽  
Damage Analysis ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Failure Loads ◽  
Experimental Findings

The present study deals with the failure analysis of pin joints by varying different geometric parameters i.e., edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio. Pin joints were prepared from the glass fiber reinforced laminates incorporating the metal inserts. A range of 2 to 5 and 3 to 6 was considered for E/D and W/D ratios, respectively. The stress around the hole was redistributed by incorporating the metal inserts in the hole to increase the load carrying capacity. To predict the failure loads and failure modes numerically, progressive damage analysis along with Hashin failure criteria was used in the pin joints. Strength of the pin joints increased in the range of 65 per cent to 92 per cent with metal insert due to the redistribution of the stresses around the hole. Progressive damage analysis gave a good correlation with experimental findings. Thereafter, the strength of the joint was predicted by varying the thickness of the metal inserts.

scholarly journals Efficiency and Stiffness of the Single Lap Bolt Joints in Glass Epoxy Composites

2019 ◽  
Vol 69 (3) ◽  
pp. 280-289
Author(s):  
Jaspreet Singh ◽  
Kulwinder Singh ◽  
J. S. Saini
Keyword(s):  
Failure Modes ◽  
Failure Load ◽  
Characteristic Curve ◽  
Joint Stiffness ◽  
Failure Criteria ◽  
Hole Diameter ◽  
Outer Diameter ◽  
Joint Efficiency ◽  
Failure Loads ◽  
Joint Characteristic

The present work deals with the investigations on the joint efficiency and the joint stiffness of the single lap bolt joint made of two dimensional woven glass fibre reinforced composite materials. The effect of joint geometry, bolt pretension and washer has been determined on the bolt joint performance. To estimate the effect of geometric parameters; the edge-to-hole diameter (e/d) and width-to-hole diameter (w/d) ratios are varied from 3 to 4 and 3 to 5, respectively. To study the worst loading conditions; the bolt pre-tension is set to zero, whereas 5 Nm torque is applied to investigate the joint in fully clamped conditions. Two different sizes of washer i.e., the outer diameter of 12 mm and 16 mm have been studied to estimate the effect of the washer on failure load, joint stiffness, and joint efficiency. Progressive damage analysis has been performed on the single lap bolt joint. Characteristic curve method along with Tsai-Wu failure criteria has been used for the prediction of the failure loads and failure modes. The joint stiffness and the failure load of the joint are increased with the increase of w/d ratios. However, the joint efficiency was negatively influenced by w/d ratio.

The Effects of Seawater Immersion on the Bearing Strength of Woven-Glass–Epoxy Prepreg Pin-Loaded Joints

2011 ◽  
Vol 21 (2) ◽  
pp. 153-170 ◽  
Author(s):  
AyŞe Öndürücü
Keyword(s):  
Failure Modes ◽  
Failure Load ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Natural Seawater ◽  
Bearing Strength ◽  
Specimen Width ◽  
Bearing Load ◽  
Mechanically Fastened ◽  
Ultimate Failure

This study considers the bearing strengths and failure modes of woven-glass–epoxy prepreg composite mechanically fastened joints. For the study, the specimens were immersed in natural seawater in the laboratory for over 1 year. The edge distance-to-hole diameter ( E/ D) ratio and the specimen width-to-hole-diameter ratio ( W/ D) were systematically altered during experiments. Failure modes were determined by observing the failure regions on the specimens. Damage progression in pin-loaded specimens prepared from woven-glass–epoxy prepreg was also examined using a scanning electron microscopy for three different percentages of ultimate failure load. According to the experimental investigation results, it was observed that the bearing load values obtained from the specimens immersed in seawater decreased considerably in comparison to unimmersed specimens.

Hygrothermal effects on mechanical joints prepared from fiber reinforced plastic nanocomposites

2019 ◽  
Vol 53 (26-27) ◽  
pp. 3875-3891
Author(s):  
Kulwinder Singh ◽  
JS Saini ◽  
H Bhunia ◽  
S Ray Chowdhury
Keyword(s):  
Glass Fiber ◽  
Barrier Properties ◽  
Hole Diameter ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Control Factors ◽  
Glass Fiber Reinforced ◽  
Different Temperatures ◽  
Nanoclay Content ◽  
Woven Glass Fiber

The present work deals with the hygrothermal aging of the bolt joints prepared from glass fiber reinforced plastics. To investigate the effect of nanoclay on joint performance, nanoclay content was varied from 0 to 5 wt%, with laminates prepared from 3 wt% of nanoclay content demonstrating the best mechanical properties. Nanoclay acts as a mechanical interlock between the fiber and the epoxy and thus improves the interfacial bonding. A good dispersion of nanoclay also improves moisture barrier properties which in turn reduces the degradation of the composite material hygrothermal conditions. Bolt joints were prepared from woven glass fiber reinforced laminates incorporating 3 wt% of nanoclay content. To design the bolt joint, ASTM D5961 was used and the geometric parameters, i.e. edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio were fixed to 5 and 6, respectively. Three different temperatures, i.e. 25℃, 50℃ and 75℃ were considered for the aging to three different duration of exposure, i.e. 1, 2 and 3 weeks. The effect of different levels of bolt torque, i.e. 0, 2 and 4 Nm were considered for the failure analysis of the joint. A full factorial design of experiment was conducted on important control factors, i.e. water temperature, exposure time, bolt torque and material variation. It was found that the hygrothermal conditions degraded the material with temperature as the most contributing factor.

Rainwater effect on bearing strength of glass–epoxy laminated composite pinned joints

2016 ◽  
Vol 50 (30) ◽  
pp. 4269-4278 ◽  
Author(s):  
Onur Sayman ◽  
Ümran Esendemir
Keyword(s):  
Room Temperature ◽  
Failure Modes ◽  
Failure Load ◽  
Weight Ratio ◽  
Laminated Composite ◽  
Hole Diameter ◽  
Plastic Container ◽  
Specimen Width ◽  
Bearing Load ◽  
Pinned Joints

Composite materials are used in areas that have varying environmental conditions due to their advantages such as generally higher stiffness- and strength-to-weight ratio, and corrosion resistance compared to metallic alloys. This experimental study is carried out to investigate the bearing strengths and failure modes of woven glass–epoxy composite pinned joints subjected to rainwater. The specimens were immersed in rainwater in a closed plastic container indoors for 20 month periods at room temperature. The ratio of edge-distance-to-hole diameter (E/D) and the ratio of the specimen width-to-hole-diameter (W/D) were selected as parameters. Failure modes were determined by observing the failure regions on the specimens. Damage of immersed and unimmersed specimens was examined using scanning electron misroscopy for the same failure load. Experimental results showed that the bearing load values obtained from the specimens immersed in rainwater decreased in comparison to unimmersed specimens.

scholarly journals Biomechanical evaluation of a novel double rip-stop technique with medial row knots for rotator cuff repair

2020 ◽  
Vol 9 (6) ◽  
pp. 285-292
Author(s):  
Zhanwen Wang ◽  
Hong Li ◽  
Zeling Long ◽  
Subin Lin ◽  
Andrew R. Thoreson ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
Failure Modes ◽  
Failure Load ◽  
Biomechanical Properties ◽  
Gap Formation ◽  
Ultimate Failure Load ◽  
Fresh Frozen ◽  
Ultimate Failure ◽  
Cuff Repair

Aims Many biomechanical studies have shown that the weakest biomechanical point of a rotator cuff repair is the suture-tendon interface at the medial row. We developed a novel double rip-stop (DRS) technique to enhance the strength at the medial row for rotator cuff repair. The objective of this study was to evaluate the biomechanical properties of the DRS technique with the conventional suture-bridge (SB) technique and to evaluate the biomechanical performance of the DRS technique with medial row knots. Methods A total of 24 fresh-frozen porcine shoulders were used. The infraspinatus tendons were sharply dissected and randomly repaired by one of three techniques: SB repair (SB group), DRS repair (DRS group), and DRS with medial row knots repair (DRSK group). Specimens were tested to failure. In addition, 3 mm gap formation was measured and ultimate failure load, stiffness, and failure modes were recorded. Results The mean load to create a 3 mm gap formation in the DRSK and DRS groups was significantly higher than in the SB group. The DRSK group had the highest load to failure with a mean ultimate failure load of 395.0 N (SD 56.8) compared to the SB and DRS groups, which recorded 147.1 N (SD 34.3) and 285.9 N (SD 89.8), respectively (p < 0.001 for both). The DRS group showed a significantly higher mean failure load than the SB group (p = 0.006). Both the DRS and DRSK groups showed significantly higher mean stiffness than the SB group. Conclusion The biomechanical properties of the DRS technique were significantly improved compared to the SB technique. The DRS technique with medial row knots showed superior biomechanical performance than the DRS technique alone.

Accelerated weathering of bolted joints prepared from woven glass fiber-reinforced nanocomposites

2019 ◽  
Vol 233 (10) ◽  
pp. 2108-2125
Author(s):  
Kulwinder Singh Chani ◽  
JS Saini ◽  
H Bhunia
Keyword(s):  
Tensile Strength ◽  
Glass Fiber ◽  
Accelerated Aging ◽  
Hole Diameter ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Fiber Matrix ◽  
Nanoclay Content

This work deals with the accelerated aging of the bolted joints prepared from glass fiber-reinforced nanocomposite laminates. ASTM D5961 was used to design the bolted joint, and the geometric parameters, i.e. width-to hole-diameter ( W/ D) ratio and edge distance-to-hole diameter ( E/ D) ratio were fixed to 6 and 5, respectively. ASTM D1544 was used for accelerated aging, and a maximum of 500 h cyclical ultraviolet exposure, 8 h of ultraviolet radiation at 60 ℃ followed by 4 h of condensation at 50 ℃, was given to the specimens. A full factorial design of experiment was conducted on important control factors, i.e. aging time, bolt torque, and material variation, using response surface methodology. To investigate the effect of nanoclay content, a range of 0–5 wt% was investigated. Specimens with 3 wt% of nanoclay demonstrated optimum tensile strength and were selected to manufacture the bolted joint. Nanoplatelets having high aspect ratio increased the specific surface area and thus the tensile strength of the nanocomposite. It was found that the strength of the joints prepared with and without the nanoclay content decreased with the increase in the duration of aging. However, the joints with the nanoclay content had higher failure loads. The strength retention in the joints with nanoclay content was more in comparison to the joints made with neat epoxy. Nanoclay acted as a mechanical interlock at the fiber–matrix interface and improved the interfacial bond strength. A good dispersion of nanoclay also acts as a barrier to the moisture, which eventually reduces the degradation of the composite material due to the lesser fiber–matrix de-bonding under accelerated aging conditions.

Progressive failure analysis of fiber-reinforced laminated composites containing a hole

2017 ◽  
Vol 27 (7) ◽  
pp. 963-978 ◽  
Author(s):  
Hadi Bakhshan ◽  
Ali Afrouzian ◽  
Hamed Ahmadi ◽  
Mehrnoosh Taghavimehr
Keyword(s):  
Failure Analysis ◽  
Failure Modes ◽  
Progressive Failure ◽  
Composite Plates ◽  
Failure Criteria ◽  
Element Analysis ◽  
Progressive Failure Analysis ◽  
Numerical Predictions ◽  
Open Hole ◽  
Failure Loads

The present work aims to obtain failure loads for open-hole unidirectional composite plates under tensile loading. For this purpose, a user-defined material model in the finite element analysis package, ABAQUS, was developed to predict the failure load of the open-hole composite laminates using progressive failure analysis. Hashin and modified Yamanda-Sun’s failure criteria with complete and Camanho’s material degradation model are studied. In order to achieve the most accurate predictions, the influence of failure criteria and property degradation rules are investigated and failure loads and failure modes of the composites are compared with the same experimental test results from literature. A good agreement between experimental results and numerical predictions was observed.

scholarly journals A Design Method to Induce Ductile Failure of Flexural Strengthened One-Way Reinforced Concrete Slabs

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7647
Author(s):  
Huy Q. Nguyen ◽  
Tri N. M. Nguyen ◽  
Do Hyung Lee ◽  
Jung J. Kim
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
Design Method ◽  
Concrete Slab ◽  
Ductile Failure ◽  
Reinforced Concrete Slabs ◽  
Failure Loads ◽  
Ultimate Failure ◽  
Rc Slabs

Strengthening existing reinforced concrete (RC) slabs using externally bonded materials is increasingly popular due to its adaptability and versatility. Nevertheless, ductility reduction of the rehabilitated flexural members with these materials can lead to brittle shear failure. Therefore, a new approach for strengthening is necessary. This paper presents a methodology to induce ductile failure of flexural strengthened one-way RC slabs. Ultimate failure loads can be considered to develop the proposed design methodology. Different failure modes corresponding to ultimate failure loads for RC slabs are addressed. Flexural and shear failure regions of RC slabs can be established by considering the failure modes. The end span of the concrete slab is shown for a case study, and numerical examples are solved to prove the essentiality of this methodology.

To study the contribution of different geometric parameters on the failure load for multi holes pin joints prepared from glass/epoxy nanoclay laminates

2017 ◽  
Vol 52 (5) ◽  
pp. 629-644 ◽  
Author(s):  
Manjeet Singh ◽  
JS Saini ◽  
H Bhunia
Keyword(s):  
Taguchi Method ◽  
Failure Modes ◽  
Failure Load ◽  
Characteristic Curve ◽  
Free Edge ◽  
Failure Criteria ◽  
Geometric Parameters ◽  
Unidirectional Glass ◽  
Curve Method ◽  
Parameters Analysis

The present work aims to analyze the strength and failure modes for the multi holes pin joint configurations made from unidirectional glass/epoxy nanoclay laminates. The geometric parameters, i.e. the distance from the free edge of the specimen to the diameter of the first two holes (E/D) ratio, the distance between two holes along the length of the specimen to the diameter of the hole (F/D) ratio, the distance between the two holes along the width of the specimen to the diameter of the hole (P/D) ratio and side width to diameter (S/D) ratio were studied for their effect on strength and failure modes of the joint. Design of experiment with Taguchi method was used for the optimization of different geometric parameters. Analysis of variance was applied to determine the influence of individual geometric parameter on the strength of the joint. The results demonstrate that the E/D and F/D ratios are the most significant parameters to increase the strength of multi holes pin joint configurations. Their percentage contributions were about 62% to 65% and 23% to 26%, respectively. Thereafter, the characteristic curve method along with Tsai–Wu failure criteria was applied to compare the numerical and experimental predictions.

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