Static bending strength assessment of sandwich panels with glass/polypropylene faces and aluminum foam cores

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040016
Author(s):  
Yi-Ming Jen ◽  
Zih-He Tang
Keyword(s):  
Aluminum Foam ◽  
Failure Modes ◽  
Shear Failure ◽  
Bending Strength ◽  
Sandwich Beam ◽  
Prediction Errors ◽  
Strength Assessment ◽  
Four Point Bending ◽  
Comparison Results ◽  
The Face

The four-point bending tests were performed first on the sandwich beam with glass/polypropylene faces and aluminum foam cores. The face thickness, core height, and angle-ply directions were considered as the variables to prepare the specimens. The effects of these variables on the bending strengths and the failure modes of the studied sandwich beams were experimentally analyzed using an MTS 810 material testing system and a four-point bending jig. Experimental results show that four failure modes, i.e. face-sheet failure, local indentation, and two types of core shear failure, were observed for the specimens with various experimental variables. The theoretical strengths for the four failure modes were proposed based on the mechanical strengths of the faces and cores. Among the four theoretical strengths, the lowest one is selected as the predicted strength and the corresponding mode is the predicted failure mode. The comparison results between the predicted and experimental strengths and failure modes were provided in the study. Assessment results show that the prediction errors are found to be below 30% for most specimens.

Failure mode maps for four-point-bending of hybrid sandwich structures with carbon fiber reinforced plastic face sheets and aluminum foam cores manufactured by a polyurethane spraying process

2017 ◽  
Vol 21 (8) ◽  
pp. 2654-2679 ◽  
Author(s):  
Peter Rupp ◽  
Peter Elsner ◽  
Kay A Weidenmann
Keyword(s):  
Carbon Fiber ◽  
Failure Mode ◽  
Aluminum Foam ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Bending Tests ◽  
The Core ◽  
Four Point Bending ◽  
The Face ◽  
Spraying Process

This work focuses on failure mode maps of sandwich panels exposed to bending load, which were produced using a polyurethane spraying process. This process allows for an automated production of sandwich panels omitting a separate bonding step of the face sheets to the core. The investigated sandwich panels consisted of carbon fiber reinforced face sheets in various configurations, and four different core structures of aluminum foam or Nomex honeycomb. After production, measurements of the pores inside the core foam structures, the fiber package thickness inside the face sheets, and the density homogeneity of the core structure were made using X-ray computed tomography. The failure mode maps were based on the individual mechanical properties of the face sheets and the core, determined by mechanical testing. The critical forces determining the failure modes were partially modified to fit the application on foam core structures and face sheets with a porous matrix. The verification of the failure modes was performed with four-point bending tests. Since all tested configurations of sandwich specimens were produced using the same process route, the applied models for the creation of the failure mode maps could be verified for numerous parameter combinations. Except for two parameters with inconstant properties, the failure modes determined by the failure mode maps matched the observed failure modes determined by the bending tests.

The effect of elevated temperature on the mechanical properties and failure modes of GFRP face sheets and PET foam cored sandwich beams

2018 ◽  
Vol 22 (4) ◽  
pp. 1235-1255
Author(s):  
Mohsen Rezaei ◽  
Vasileios Karatzas ◽  
Christian Berggreen ◽  
Leif A Carlsson
Keyword(s):  
Compressive Strength ◽  
Polyethylene Terephthalate ◽  
Failure Modes ◽  
Shear Failure ◽  
Elevated Temperatures ◽  
Sandwich Beam ◽  
Standard Test ◽  
Sandwich Beams ◽  
The Face ◽  
Failure Loads

The influence of elevated temperatures on stiffness and strength of composite face sheet and polyethylene terephthalate foam cored sandwich beam has been experimentally investigated. Standard test methods and analytical failure models were used to determine the effect of elevated temperatures. The authors examined E-glass/epoxy cross-ply face laminates, polyethylene terephthalate foam, and sandwich beams consisting of glass/epoxy face laminates and polyethylene terephthalate foam core loaded in four-point flexure. The tensile properties of the face laminate were examined over a temperature range from 25 to 175°C. Compression and shear tests on the face laminate, polyethylene terephthalate foam, and sandwich beams were performed at temperatures up to 100°C. The face laminates exhibited moderate reductions of Young’s modulus and tensile strength, while the compressive strength, shear modulus, and shear strength substantially decreased at elevated temperatures. Similarly, the compressive and shear moduli as well as the compressive strength of the polyethylene terephthalate foam decreased substantially by exposure to a temperature of 100°C. The failure mode of the sandwich panels was observed to be highly dependent on temperature, distinguishing three basic failure modes, viz. core shear failure, indentation failure, and face wrinkling. The failure loads associated to these failure modes were calculated using models available in the literature. The failure loads were found to be consistent with the failure predictions and failure modes.

Design of Hybrid Sandwich Panel with Aluminum Foam Core and Carbon Fiber Reinforced Plastic Face Sheets under Three-Point Bending

2006 ◽  
Vol 111 ◽  
pp. 63-66 ◽  
Author(s):  
K. Mohan ◽  
Tick Hon Yip ◽  
Idapalapati Sridhar ◽  
H.P. Seow
Keyword(s):  
Carbon Fiber ◽  
Aluminum Foam ◽  
Failure Modes ◽  
Shear Failure ◽  
Elastic Stiffness ◽  
Foam Core ◽  
Fiber Reinforced ◽  
Three Point Bending ◽  
Structural Applications ◽  
Carbon Fiber Reinforced

Aluminum foams are very popular material for structural applications because of its attractive combination of properties. Structural performance of those foams can be enhanced by bonding them between strong and stiff face sheets such as carbon fiber reinforced plastics (CFRP). The response of hybrid sandwich panels comprising aluminum foam core and CFRP face sheets were investigated under three-point bending and measured response is verified with finite element numerical simulations. Core indentation and core shear, failure modes are identified. Experimentally measured elastic stiffness and failure load of thee tested beams were found to be in good agreement with the numerical simulation and analytical predictions.

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Failure Modes ◽  
Bending Strength ◽  
Metal Loss ◽  
Pipe Surface ◽  
Comparison Results ◽  
Mechanical Interference ◽  
Bending Capacity

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage after mechanical interference. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe tests. Artificial damage, such as a dent, metal loss, a crack, and combinations thereof, is introduced to the pipe surface in advance. Four-point bending tests are performed to investigate the structural behavior of metallic pipes in terms of bending moment–curvature diagrams, failure modes, bending capacity, and critical bending curvatures. Test results show that the occurrence of structural damage on the pipe compression side reduces the bending capacity significantly. Only a slight effect has been observed for pipes with damage on the tensile side as long as no fracture failure appears. The possible causes that have introduced experimental errors are presented and discussed. The test data obtained in this paper can be used to further quantify damage effects on bending capacity of seamless pipes with similar D/t ratios. The comparison results in this paper can facilitate the structural integrity design as well as the maintenance of damaged pipes when mechanical interference happens during the service life of pipelines.

Dynamic Response of Aluminum Foam Sandwich Panel to Transverse Impact

2013 ◽  
Vol 535-536 ◽  
pp. 485-488
Author(s):  
Zhi Hua Wang ◽  
Xin Li ◽  
Zhi Qiang Li ◽  
Long Mao Zhao
Keyword(s):  
Dynamic Response ◽  
Aluminum Foam ◽  
Failure Modes ◽  
Shear Failure ◽  
Metal Foam ◽  
Sandwich Panels ◽  
Front Face ◽  
Strain History ◽  
Transverse Impact ◽  
Cell Foam

The dynamic response of aluminum foam sandwich panels are studied experimentally by impacting the panels at mid-span with metal foam projectiles. Two types of core are considered: open-cell foam and closed-cell foam. By changing the launching speed of metal foam projectiles, different deformation/failure modes of sandwich panels are obtained. Strain history of face sheets in different positions is also recorded by strain gauges to observe its deformation mechanism. The experiment results indicated that when the strength of core is relatively small and the impulse exerted is large, erosion failure of front face and shear failure of core occurred.

scholarly journals Evaluation of punching shear capacity of two-way RC slabs without transverse reinforcement according to different provisions

2021 ◽  
Vol 15 (3) ◽  
pp. 171-184
Author(s):  
Tran Xuan Vinh ◽  
Nguyen Trung Hieu ◽  
Pham Xuan Dat ◽  
Nguyen Manh Hung
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Test Results ◽  
Flat Slabs ◽  
Comparison Results ◽  
Eurocode 2 ◽  
Effective Depth ◽  
Rc Slabs

Currently, RC flat slabs are being used commonly because of their advantages. Punching shear failure is one of the governing failure modes of RC flat slabs without column capital and drop panels. In this paper, the provisions for predicting the punching shear capacity of two-way reinforced concrete (RC) flat slabs without shear reinforcement including ACI 318-19, Eurocode 2 and TCVN 5574:2018 provisions are reviewed by mean of considering the influences of the main parameters (effective depth, compressive strength of concrete, loaded area, reinforcement ratio). A total of 169 test results collected from the literature were used to compare with the provisions. The aim of this study was to evaluate the level of applicability of predicting the punching shear capacity of two-way RC flat slabs according to these provisions. The comparison results indicated that the Eurocode 2 provision provides the most accurate prediction of punching shear capacity of two-way RC flat slabs.

Predicting failure modes of 3D-printed multi-material polymer sandwich structures from process parameters

2021 ◽  
pp. 109963622110204
Author(s):  
David L Edelen ◽  
Hugh A Bruck
Keyword(s):  
Bearing Capacity ◽  
Process Parameters ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Sandwich Structures ◽  
Sandwich Beam ◽  
Failure Model ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
The Face

The emergence of additive manufacturing (AM) technologies, such as fused deposition modeling (FDM), have enabled the realization of structures with superior mechanical performance through lightweighting and multi-material architectures. However, the complexity associated with the internal geometric features and potential material configurations have also presented new challenges in designing these structures to optimize mechanical performance. In particular, the failure mechanisms and their relationship to the load bearing capacity of the structures may vary compared to analogous structures designed using conventional manufacturing techniques. In this work, we investigate failure modes of 3 D-printed (3DP) multi-material polymer sandwich beam structures manufactured from acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) materials and subjected to three-point bend loading. Digital Image Correlation (DIC) is utilized to understand the effects of different process parameters on the mechanical response of the 3DP structures. ABS and PC dogbone tensile specimens were printed to establish the baseline properties in tension with varying raster angles and infill patterns. Multi-material sandwich beam structures were then printed with honeycomb cores using different processing and architectural parameters, and the failure modes and loads of these structures were compared with predications from a failure model for sandwich structures that accounts for the following conventional failure modes: (1) indentation, (2) face sheet bending, (3) core bending, and (4) core shear. With minor changes in the processing and geometric parameters, failure modes could be shifted from the face sheets to core bending and core shear, as evidenced by the DIC strain field measurements, and the corresponding max load-to-weight ratios could be increased. Estimations of the tensile properties of the face sheets and core were found to be sufficiently accurate when combining classical lamination theory (CLT) and rule-of-mixtures (ROM) models, while the failure model also predicted the load bearing capacity and failure mode in three-point bending with reasonable accuracy.

Characteristics of Low Temperature Degradation Free ZTA for Artificial Joint

2014 ◽  
Vol 631 ◽  
pp. 18-22 ◽  
Author(s):  
Junji Ikeda ◽  
Takayuki Murakami ◽  
Takayoshi Shimozono ◽  
Reiji Watanabe ◽  
Mikio Iwamoto ◽  
...  
Keyword(s):  
Low Temperature ◽  
Phase Stability ◽  
Mechanical Characteristics ◽  
Bending Strength ◽  
Accelerated Aging ◽  
Ceramic Materials ◽  
Wear Property ◽  
Artificial Joint ◽  
Four Point Bending ◽  
Bearing Materials

Low temperature degradation free Zirconia toughened alumina (ZTA) has been developed. It is reported that ZTA has higher mechanical strength compared to alumina due to the stress induced transformation and spontaneously transformation of zirconia phase on some ZTA have been occurred. For achieving the higher reliability of artificial joint prosthesis alternative to alumina and other ceramic materials, it is necessary to improve and validate the both mechanical characteristics and phase stability at the same time. We evaluated that microstructure, mechanical characteristics and phase stability of newly developed ZTA (BIOCERAM®AZUL). It was confirmed that four-point bending strength and weibull modulus were extreamly high, and ZTA has higher reliability. There were no significant changes and deterioration in four-point bending strength, crystal structure and wear property with and without accelerated aging test. Newly developed ZTA not only with high mechanical characteristics but also with phase stability could be quite useful as bearing materials in artificial joints for longer clinical use.

Machine learning-based failure mode identification of RCSPSW

2021 ◽  
Author(s):  
Dongqi Jiang ◽  
Shanquan Liu ◽  
Tao Chen ◽  
Gang Bi
Keyword(s):  
Machine Learning ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Tall Buildings ◽  
Shear Walls ◽  
Superior Performance ◽  
Ann Model ◽  
Mode Recognition ◽  
Wide Range

<p>Reinforced concrete – steel plate composite shear walls (RCSPSW) have attracted great interests in the construction of tall buildings. From the perspective of life-cycle maintenance, the failure mode recognition is critical in determining the post-earthquake recovery strategies. This paper presents a comprehensive study on a wide range of existing experimental tests and develops a unique library of 17 parameters that affects RCSPSW’s failure modes. A total of 127 specimens are compiled and three types of failure modes are considered: flexure, shear and flexure-shear failure modes. Various machine learning (ML) techniques such as decision trees, random forests (RF), <i>K</i>-nearest neighbours and artificial neural network (ANN) are adopted to identify the failure mode of RCSPSW. RF and ANN algorithm show superior performance as compared to other ML approaches. In Particular, ANN model with one hidden layer and 10 neurons is sufficient for failure mode recognition of RCSPSW.</p>

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