Failure Analysis of Glulam Lumber Beam Made from Meranti Lumber Pieces (Shorea SP)

The development of glue-laminated (glulam) lumber beam gives many good results. Meranti (Shorea SP) is one of the construction lumber that can be used as glulam to optimize its use. The limitation of the glulam lumber beam is the limited length of the lumber, so it must be joined to get a certain length. The lumber available in the market on average has a limited size and cross-sectional length. The larger the cross-sectional size and length of the lumber make the higher the price. Used lumber and residual lumber also have many weaknesses, such as the length of suitable lumber is too short, lumber defects, and lumber damages. Further research needs to be done to optimize the use of new, used, and residual meranti lumber through the use of lumber pieces as a glulam lumber beam maker. Standard specimen and test based on ASTM D-198. Glulam lumber beam is made from pieces of meranti lumber planks of certain length which are arranged into lamina beam with the size of 5.5x9.5x150 cm3. Variations in the length of the pieces of meranti lumber planks for making glulam lumber beam, among others, 40 cm, 50 cm, 60 cm, 50 cm with full length lowest layer and 150 cm (full length). The adhesive used is polyurethane glue. The span between supports is 130 cm. The beam is tested for center point loading. The analysis results show that the joints on the outermost layer that receive tensile stress of the glulam lumber beam can cause weakening in the beam because the tensile strength of the adhesive is weaker than the tensile strength of lumber. Failure at the tensile joint of the outer layer of the beam can trigger a shear failure mode. Design of joints should not be placed on layers that are subject to tensile stresses so as not to trigger shear failure modes so that the strength of the glulam lumber beam can be optimal.

Download Full-text

Failure mechanism of hollow tree trunks due to cross-sectional flattening

Royal Society Open Science ◽

10.1098/rsos.160972 ◽

2017 ◽

Vol 4 (4) ◽

pp. 160972 ◽

Cited By ~ 6

Author(s):

Yan-San Huang ◽

Fu-Lan Hsu ◽

Chin-Mei Lee ◽

Jia-Yang Juang

Keyword(s):

Urban Areas ◽

Failure Modes ◽

Shear Failure ◽

Maximum Shear Stress ◽

Mode Iii ◽

Buckling Mode ◽

Cross Sectional ◽

Longitudinal Splitting ◽

Bending Failure ◽

Hollow Tree

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t / R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t / R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 < t / R < 0.06, 0.06 < t / R < 0.27 and 0.27 < t / R < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings.

Download Full-text

Temperature-dependent shear failure modes and tensile strength model of CNT/polymer nanocomposites

Composites Communications ◽

10.1016/j.coco.2021.100726 ◽

2021 ◽

pp. 100726

Author(s):

Xuyao Zhang ◽

Weiguo Li ◽

Shifeng Zheng ◽

Ziyuan Zhao ◽

Yi He ◽

...

Keyword(s):

Tensile Strength ◽

Polymer Nanocomposites ◽

Failure Modes ◽

Shear Failure ◽

Strength Model ◽

Temperature Dependent

Download Full-text

3 failure limits to relief

10.5194/egusphere-egu2020-2348 ◽

2020 ◽

Author(s):

Anne Voigtländer ◽

Rachel C. Glade ◽

Jens M. Turowski

Keyword(s):

Tensile Strength ◽

Material Properties ◽

Failure Modes ◽

Shear Failure ◽

Slope Angle ◽

Rock Failure ◽

Material Strength ◽

High Mountain ◽

Maximum Slope ◽

Strength Limit

Reaching the top of a high mountain is a great experience, yet there seem to be several limits. One is the relief of the mountain itself, which constitutes the driving stress consisting of the height, h, and density, &#961; of the mass, accelerated by gravity, g and modulated by the slope, &#945;. The material strength required to balance this stress defines the limit to relief. There are three failure modes in which the material strength can be surpassed: shear, compression, and tension. Failure criteria established for shear and compression have been demonstrated to be useful in certain settings, but don&#8217;t hold in steep (50-90&#176;), hard and rocky landscapes. For those, we propose a tensile strength limit criterion (TSL). Due to the Poisson effect of normal stress (&#963;n), indirect tensile stresses (&#963;t) arise near free surfaces. The magnitude of these stresses is defined by the Poisson&#8217;s ratio (&#957;) of the lithology and the relief. First-order estimates of different lithologies and their material properties are in good agreement with the height of cliffs and slopes of the same lithology. Similar to the approach by Schmidt and Montgomery (1995) predicting bulk, slope scale material properties from relief, we can invert the tensile strength limit criterion. By this, we can infer material tensile strength and Poisson&#8217;s ratio from the maximum slope heights and angle on Earth, and beyond!In terms of dynamics, the tensile strength limit criterion (TSL) predicts critical yielding at the foot of the slope, causing surface parallel fractures that would lead to further critical yielding and failure slope upward. This pattern of progressive rock failure has been observed in steep rock walls, like El Capitan or Half Dome in Yosemite National Park.We propose this solely geometrically and stress-controlled criterion not contrary but in addition to existing limit criteria. Implications of the three failure limits to relief are that, (i) over-steepening doesn&#8217;t necessarily exist, as there is not only a threshold slope angle but also a threshold height, (ii) there is a transition from one dominant limit and failure mechanism to the other, shifting from shear failure and sliding to toppling and fall, and (iii) internal material property changes, due to chemical and/or mechanical weathering, and subcritical crack growth can evoke a progressive reorganisation of yielding and potential rock failure without external triggering events.

Download Full-text

Effect of Corrosion in the Transverse Reinforcements in Concrete Beams: Sustainable Method to Generate and Measure Deterioration

Sustainability ◽

10.3390/su12198105 ◽

2020 ◽

Vol 12 (19) ◽

pp. 8105

Author(s):

P. Castro-Borges ◽

C. A. Juárez-Alvarado ◽

R. I. Soto-Ibarra ◽

J. A. Briceño-Mena ◽

G. Fajardo-San Miguel ◽

...

Keyword(s):

Shear Strength ◽

Failure Modes ◽

Shear Failure ◽

Corrosion Potential ◽

Concrete Beams ◽

Ultimate Shear Strength ◽

Cross Sectional ◽

Mass Losses ◽

Consistent Method ◽

Theoretical Results

A consistent method to generate and measure deterioration by corrosion in transverse reinforcements for concrete beams is presented and discussed in this work. This approach could be applied in other circumstances, such as bending, compression or combinations of stresses, with comparable results and therefore can be used to ensure sustainability. In marine environments, macro-cells are produced primarily from a transverse reinforcement, which works as an anode and therefore becomes a critical part of the structural analysis. To evaluate the adaptation efficiency of our proposed method, the corrosion potential, mass losses and cross-section reductions of the steel were measured. The shear stress behavior of the beams was investigated, including beam responses to load deformations, failure modes and cracking. The method ensured that all the beams exhibited a shear failure from diagonal stress with almost 50% less deflection when mechanically tested. The critical cross-sectional area, calculated according to the experimental diameter with the greatest cross-sectional loss due to the corrosion of the deteriorated stirrup, proved to be a reliable value for predicting the ultimate shear strength of concrete beams deteriorated by severe corrosion. A reduction of up to 30% in the shear strength of deteriorated versus non-deteriorated beams was found. Additional results showed that there is a correlation between the experimental and theoretical results and that the method is reproducible.

Download Full-text

Infrared Diagnostics of Free Charge Carriers in Silicon Nanowires

International Journal of Nanoscience ◽

10.1142/s0219581x19400301 ◽

2019 ◽

Vol 18 (03n04) ◽

pp. 1940030 ◽

Cited By ~ 1

Author(s):

A. I. Efimova ◽

E. A. Lipkova ◽

K. A. Gonchar ◽

A. A. Eliseev ◽

V. Yu. Timoshenko

Keyword(s):

Silicon Nanowires ◽

Crystalline Silicon ◽

Free Charge Carrier ◽

Charge Carrier Concentration ◽

Attenuated Total Reflection ◽

Free Charge ◽

Cross Sectional ◽

Text Type ◽

Cross Sectional Size ◽

Potential Applications

Free charge carrier concentration in arrays of silicon nanowires (SiNWs) with cross-sectional size of the order of 100[Formula: see text]nm was quantitatively studied by means of the infrared spectroscopy in an attenuated total reflection mode. SiNWs were formed on lightly-doped [Formula: see text]-type crystalline silicon substrates by metal-assisted chemical etching followed by additional doping through thermoactivated diffusion of boron at 900–1000∘C. The latter process was found to increase the concentration of free holes in SiNWs up to [Formula: see text][Formula: see text]cm[Formula: see text]. Potential applications of highly doped SiNWs in thermoelectric energy converters and infrared plasmonic devices are discussed.

Download Full-text

Instability analysis of a filament-wound composite tube subjected to compression/bending

Advanced Composites Letters ◽

10.1177/0963693519877417 ◽

2019 ◽

Vol 28 ◽

pp. 096369351987741

Author(s):

Gyula Szabó ◽

Károly Váradi

Keyword(s):

Failure Modes ◽

Slenderness Ratio ◽

Equivalent Stress ◽

Bending Test ◽

Test Machine ◽

Fe Model ◽

Rubber Tube ◽

Nonlinear Buckling ◽

Cross Sectional ◽

Composite Tube

The aim of this study is to investigate the global buckling of a relatively long composite cord–rubber tube subjected to axial compression and its cross-sectional instability due to bending by a macromechanical nonlinear finite element (FE) model (nonlinear buckling analysis). Composite reinforcement layers are modelled as transversely isotropic ones, while elastomer liners are described by a hyperelastic material model that assumes incompressibility. Force–displacement, equivalent strain, equivalent stress results along with oblateness and curvature results for the complete process have been presented. It is justified that bending leads to ovalization of the cross section and results in a loss of the load-carrying capacity of the tube. Strain states in reinforcement layers have been presented, which imply that the probable failure modes of the reinforcement layers are both delamination and yarn-matrix debonding. There is a significant increase in strains due to cross-sectional instability, which proves that the effect of cross-sectional instability on material behaviour of the tube is crucial. A parametric analysis has been performed to investigate the effect of the member slenderness ratio on cross-sectional instability of the composite tube. It shows that Brazier force is inversely proportional to the slenderness ratio. It further shows that higher oblateness parameters occur in case of a lower slenderness ratio and that cross-sectional instability takes place at a lower dimensionless displacement in case of a lower slenderness ratio. FE results have been validated by a compression/bending test experiment conducted on a tensile test machine.

Download Full-text

Tensile Properties of Low Nickel Austenitic Stainless Steel at Elevated Temperatures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.159.346 ◽

2012 ◽

Vol 159 ◽

pp. 346-350

Author(s):

Shu Min Liu ◽

Jian Bin Zhang

Keyword(s):

Tensile Strength ◽

Stainless Steel ◽

Elevated Temperatures ◽

Peak Stress ◽

Temperature Curve ◽

Delta Ferrite ◽

Cross Sectional ◽

Different Temperatures ◽

Increasing Temperature ◽

Reduction Percentage

The elevated temperature short-time tensile test with the sample of casting low nickel stainless steel was conducted on SHIMADZU AG-10 at ten temperatures 300, 500, 600, 700, 800, 950, 1000, 1050, 1100, and 1250°C, respectively. The stress-strain curves with the thermal deformation at the different temperatures, the peak stress intensity-temperature curve, and the reduction percentage of cross sectional area-temperature curve were obtained. Metallographic test samples were prepared and the morphology of deforming zone was observed by optical microscopy. The experimental results show that the tensile strength of the test samples decreases with increasing temperature. From 300 to 800°C, the work harding occurred and the tensile strength increases with increasing strain. The work softening occurred and the tensile strength decreases with increasing strain at temperatures of 800 to 1250°C. The minimum value of reduction percentage was measured at 800 °C. The austenite and delta-ferrite are the main phase in the tested samples. When the tensile temperatures are increased to 1200°C, the delta-ferrite became thinner and broke down to be spheroidized.

Download Full-text

Effect of Pre-Oxidized CuO Layer in Joining between Polyethylene Terephalate (PET) and Copper (Cu) by Using Pulsed Nd:YAG Laser

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.129-131.714 ◽

2010 ◽

Vol 129-131 ◽

pp. 714-718 ◽

Cited By ~ 2

Author(s):

Farazila Yusof ◽

Yoshiharu Mutoh ◽

Yukio Miyashita

Keyword(s):

Laser Irradiation ◽

Nd:Yag Laser ◽

Shear Failure ◽

High Heat ◽

Experimental Result ◽

Joint Interface ◽

Intimate Contact ◽

Cross Sectional ◽

Pulsed Nd:Yag Laser ◽

Oxide Particles

In the present study, effect of pre-oxidized (PO) CuO layer in the joining between polyethylene terephalate (PET) and copper (Cu) by using pulsed Nd:YAG laser was investigated. The experimental result for PET/PO Cu (with pre-oxidized layer) and PET/Cu (without pre-oxidized layer) were presented in this paper. The results showed the pre-oxidation surface improved the welding efficiency. The welded area and tensile shear failure load (TSFL) of PET/PO Cu joint were increased when pre-oxidized layer was introduced. This indicates that high heat was absorbed during laser irradiation of PET/PO-Cu joint compare to PET/Cu joint. On the other hand, the fracture surface of PET/PO-Cu showed the presence of Cu and Cu oxide particles in the PET side. While in case of PET/Cu, no occurrence of Cu particles can be observed. The presence of Cu oxide particles and Cu particles were believed may increase PET/PO Cu joint shear force. From the cross-sectional observation of PET/PO Cu joint interface, it was found that an oxide layer in the laser irradiation area was removed and PET seemed to have intimate contact with Cu surface.

Download Full-text

Machine learning-based failure mode identification of RCSPSW

IABSE Congress, Christchurch 2021: Resilient technologies for sustainable infrastructure ◽

10.2749/christchurch.2021.1150 ◽

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

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), K-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.

Download Full-text

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

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4052907 ◽

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.

Download Full-text