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DOI : 10.23883/IJRTER.2017.3144.XNO0N 267
ANALYSYS & OPTIMIZATION OF HYDRAULIC EXCAVATOR
BUCKET TEETH USING FEM
Shailesh sharma1, Alok Sharma2 1,2 Mechanical Engineering Department, SSTC Bhilai
Abstract— In this paper various configurations of the bucket teeth have been designed in order to
perform static analysis. The analysis has been carried out by using ANSYS14.5 where various
configurations of teeth are designed as per SAE J1179 standard and using boundary condition for the
maximum digging force condition all the design teeth are subject to maximum force. The effect of
maximum digging force has been observed on maximum tooth deformation and Maximum
Equivalent Von-Mises stress. In order to validate the obtained results are compared with the
available literature and the results are within acceptable limit. Moreover, the effect of fillet on the
teeth tip has been observed in terms of maximum total deformation and Von mises stresses. And the
optimum condition of the fillet has been proposed for the all the configuration of the bucket teeth.
Keywords—Bucket excavator, Bucket Teeth, Deformation, Failure teeth
I. INTRODUCTION
A hydraulic excavator (digger) is an outsized vehicle that is build up for demolition and
excavation purposes. A conventional hydraulic excavator consists of various parts but the basic
prime parts are boom, chassis, and bucket, and move using wheels or tracks. They are available in a
wide range in size and function, an instance of which is the comparable but smaller “mini
excavator.” All versions are usually designed for the same intentions. Hydraulic excavators weigh
lying 3,000 and 2 million pounds and their speed varies between 19 HP and 5,000 HP.
Conventionally, Hydraulic excavator bucket is made up of selling steel and normally tooth
present, which is protruding from the cutting edge, is to disrupt hard material and prevents from
wearing-and-tearing of the bucket. The excavator bucket tooth has to stand heavy loads of materials,
for example, wet soil and rock furthermore, it also subjected to abrasion wear because of the abrasive
nature of soil particles when tooth acting to disintegrate material. Generally, for making tooth of
excavator bucket alloy steel is used along with the addition of some other wear resistant materials so
that its life will improve against abrasive wear. Using alloy along with solid steel is basically due to
having both good toughness and abrasive resistance as of having direct contact of metallic
components with the soil constituents. Therefore, better selection of tooth material and tooth design
should be undertaken in order to prevent from bucket tooth failure.
II. LITERATURE REVIEW
Maciejewski et al. 2004 conduct an experiment to investigate soil cutting problem. And
concluded that the tool width equalled the width of the soil bin, the soil cutting problems might be
treated as plane strain processes. Moreover in their next paper they conduct a new experiment to
analyze the bucket equipped with teeth. And the effect of no. of teeth and teeth spacing has been
examined in order to enhance the digging cycle efficiency.
Coetzee et al.2007 presents an 2Dimensional discrete and continuum modelling of excavator
bucket filling. Discrete element method and material-point method are used and compared with
experimental results and conclude that The DEM model does not accurately predict the material flow
during filling, while the polar and non-polar techniques are more accurate.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 268
Knight 2009 analyzed the shovel dipper teeth and evaluate the Optimal replacement intervals.
a novel technique called ‘grouped failure data with multiple suspensions has been used and conclude
that using this replacement interval a saving of US$ 300,000 per shovel per year can be achieved.
Eugeniusz et al 2010 examined the failure caused by fractured shaft of the bucket wheel. To
analyze the failure discrete model has been developed and using FEM technique analysis has been
carried out. At the fractured region Macroscopic and microscopic image has been taken o analyze the
microscopic characteristics so that such failure of shaft can be be prevented in future.
Jovancic et al. 2011 diagnose Load-Bearing capacity of bucket wheel excavator and found
that the force exerted during excavation operation are required to find these forces for better design
of tool, backhoe parts and for trajectory planning.
Miodrag et al. 2011 examined the failure of bucket wheel caused by residual stresses in
welded joints using FEM approach. The results are compared with the numerical–experimental result
and revealed that the combination of working (dynamic) and residual (static) stress can be over the
limit lines of modified Goodman’s.
Babu and Venu et al.2014 optimized the excavator bucket using finite element method. They
develop and bucket for PC-09 and Zaxis-8-1 using solid works and imported in ANSYS for transient
analysis. They modified some parameters and proposed a optimum design.
Kalpak et al 2015 The Excavator bucket tooth have to bear heavy loads of materials like soil,
rock and subjected to abrasion wear due to the abrasive nature of soil particles. Its tooth got damaged
due to abrasive wear and impact load. This paper deals with review of Excavators bucket tooth
analysis to find out its actual failure.
III. METHODOLOGY
The Bucket teeth has been modeled by using ANSYS 14.5 and it is was discretized into 7208
elements with 39127 nodes For bending and contact stress analysis of the bucket tooth the material
properties has been tabulated in table 5.1 and the dimensions of the teeth are detailed in figure 1 the
develop teeth are as per SAE standards. The meshed teeth in ANSYS 14.5 is shown in figure 2. The
boundary condition applied to the teeth is detailed in Figure 3
Table 5.1 Tooth Material properties [10, 11, 12]
Properties Alloy steel Hardox 500
Density (kg/ m3) 7850
Modulus of elasticity (MPa) 2.1*105
Poisson's ratio 0.29
Yield strength (MPa) 1000
Ultimate tensile strength(MPa) 1250
Impact toughness (J) 30
Brinell hardness 370-500
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 269
Figure 1 Tooth Dimension [10, 12]
Standard Teeth
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 270
Fanggs Digg Teeth
Long Teeth
Twin Tiger Teeth
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 271
Tiger Teeth
Figure 2 Meshed Teeth
Figure 3 Boundary condition for tooth
IV. Result and Discussion
Figure 4 Validation of Maximum total deformation with respect to different tooth configuration
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 272
Figure 5 Validation of Maximum Equivalent Von-mises stress with respect to different tooth configuration
Figure 4-5 shows the validation of Maximum total deformation and Maximum Equivalent Von-
Mises stress with respect to different tooth configuration. It has been observed that the obtained
results from Present finite analysis (ANSYS) of various tooth has been compared with the work of
Bilal and Abid [10] and observed that the result shows good agreement and are in the acceptable
range.
Percentage variation has also been tabulated and it has been observed that the maximum deviation in
maximum total deformation has been seen for Long Teeth i.e. ±14% .While minimum for Tiger teeth
i.e. ±0.41%. Similarly for Maximum Equivalent Von-Mises stress maximum total deformation has
been seen for Fanggs Digg Teeth i.e. ±9.68% .While minimum for Abbrasion teeth i.e. ±0.42%.
The variations in results are mainly due to different mesh sizing and taken assumptions during
analysis.
Figure 6.and 7 illustrates the effect of Fillet radius on the Maximum total deformation and Maximum
Equivalent Von-Mises stress of the Tiger Teeth. It has been observed that the the Maximum total
deformation and Maximum Equivalent Von-Mises stress drastically decreases as the fillet radius
increases. This means that introducing fillet reduce the stress level at the tip of the tooth. It has been
analyzed that fillet radius above 1mm to 4mm the teeth are under safe zone and can withstand wide
range of force.
From the above, it can also be concluded that increasing fillet radius from 2mm to 4mm i.e. (100%),
the stress level can be decreased by 43.6025% respectively. Similarly, the rate of deformation can
also be reduced by 38.179%.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 273
Figure 6 Effect of Fillet radius on the Maximum total deformation and Maximum Equivalent Von-mises
stress of the Tiger Teeth
Figure 6.18 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger
Teeth
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 04; April - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 274
Figure 7 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger Teeth
V. CONCLUSIONS
On the basis of finite element analysis of exactor bucket teeth following conclusions has been drawn
which are as follows:
The obtained result has been compared with the Bilal and Abid [18] and shows good agreement
and varies in the range of ±0.2-±14.
The effect of introducing fillet at the tip of the teeth has been observed for all configurations of
the teeth and it has observed that majorly in most of the cases increasing fillet radius the
Maximum total deformation and Maximum Equivalent Von-mises stress decreases significantly.
It can be concluded that the fillet radius 0 to 1mm the teeth’s are un-safe and has maximum
possibility of failure. While, for fillet radius 2 to 4mm the teeth’s are under safe limit. This is
due to their Von-mises stress lying below their maximum yield strength. i.e. 1000/2 =500MPa,
where 2 is factor of safety.
It has been observed that the twin tiger tooth is not suitable for excavation of rigid surface. As it
can be used for excavation of densely compacted soil/material normally in such cases, teeth are
not subjected to such high force.
It has been found that the optimum fillet radius should be taken between 2-3mm
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