aluminum alloys and behavior under cyclic loading in...

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International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 11, November 2017, pp. 746–752, Article ID: IJCIET_08_11_076

Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=11

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

ALUMINUM ALLOYS AND BEHAVIOR UNDER

CYCLIC LOADING IN JOINTS OF TRUSS

STRUCTURES

Ragip Hadri

Department of Civil Engineering, University of Prishtina, Bregu I Diellit P.N,Prishtine

Ali Muriqi*

Department of Civil Engineering, University of Prishtina, Bregu I Diellit P.N,Prishtine

*Corresponding author

ABSTRACT

Aluminum is the second most widely specified metal in building after steel, and is

used in all sectors from commercial building to domestic dwelling. This paper

contains overview of use of aluminum in building construction, specifically in

connections of trust elements. This paper also contains the properties of aluminum

alloys, setup of testing, advantages and no advantages under the cyclic loads. The

used properties parameters during the testing are compared with the parameters

given by the manufacturer, the standards of the European Aluminum Association and

Eurocode 9. Testing of the models was performed on a hydraulic press (pulsator),

Amsler''.The behaviour of join was focused in long period during the testing to

analyze the failure mode and to compare with dynamic factor using in analytical

method using during the experiment.

This concept was reasonly accepted such dynamic coefficient in the diagonal D1,

such trust element in value γD = 1,6. European Aluminium Association still doing

research on getting the dynamic coefficients of fatigue for aluminum alloys and this

research will present the contribution in this regard.

Keywords: Aluminum Alloys, Connections, Testing, Cyclic loads, Failure

Cite this Article: Ragip Hadri and Ali Muriqi, Aluminum Alloys and Behavior under

Cyclic Loading in Joints of Truss Structures, International Journal of Civil

Engineering and Technology, 8(11), 2017, pp. 746–752

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=11

1. INTRODUCTION

The increasing use of engineering materials in different types of loading requires that the

materials have good mechanical properties in these conditions. Fatigue is one of the principle

damage mechanisms or materials operating under loading conditions. During the cyclic

Ragip Hadri and Ali Muriqi


loading process the behavior of the structure will be under larger strain deformation, crack

initiation and growth. Finally the material or structure may fail in different modes, fatigue,

rupture, large deformation, or brittle failure of the materials in connection or joints of

structure.[1].

The fundamental principles of behavior during the analytical and testing are same such in

steel constructions:

• Chemical analysis of aluminum alloy

• Mechanical properties of materials, in our case , testing the tensile strength

• Mode of failure during the testing

• Testing set up

• Apply the cyclic loads

For different elements of trust structure during the research are analyzing the three

aluminum alloys: EN AW 6063 T66; EN AW 6028 T656; EN AW 6028 T6. For all types of

materials are make the analysis before the trust is designed.

The focused point was in joints and effects of bolts in this positions using the opening for

connections and the compatibility between the materials and bolts.[1,2,3].

2. MATERIALS AND EXPERIMENTAL PROCEDURES

The tested materials were aluminum alloys, namely the AW 6063 T66; AW 6028 T656 and

AW 6028 T6 alloys. The chemical composition is shown in “Table 1”; Metallographic

Analyses presented in “Fig. 1” has been examined in and their mechanical properties are

presented in “Table 2”. An axial tensile test has been made using 3 samples for each alloy,

and they were prepared according ASTM E660 “Fig. 2”.Tensile tests were performed on

tensile test machine to obtain monotonic stress.[9,10,11].

Table 1 Chemical analysis of aluminum alloys

Symbol of elements

and alloy Si% Fe% Cu% Mn% Mg% Zn% Ag% Bi% Cd%

Profile L50x5

EN AW 6063 T66 0,49 0,21 0,084 0,04 0,49 0,030 0,510 0,0003 0,007

Plate thicknees-6mm

EN AW 6028 T651 0,89 0,20 0,095 0,35 0,91 0,038 0,503 0,0003 0,007

Joint elements –Bolts

EN AW 6028 T6 0,83 0,18 0,210 0,40 0,65 0,020 0,510 0,0002 0,007

Examinations of Metallographic analysis is used the microscope with enlargement 1:500,

and the structure is presented in “Fig.1”.

EN AW 6063 T66 EN AW 6028 T651 EN AW 6028 T6

Figure 1 Images of Metallographic analysis of aluminum alloys

Aluminum Alloys and Behavior under Cyclic Loading in Joints of Truss Structures


The mechanical properties are done in prepared samples examined in standard process

according the ASTM E660 using the type of equipment “Amsler”, and the failure of samples

for three types of aluminum alloys is presented in “Fig.2”.

Figure 2 Failure of different types of examined aluminum alloys

Behaviour of materials-aluminum alloys under applied the loads and deformations is

presented through the chart “σ-ε” , in fig. 3, and Modulus of Elasticity , presented in “table 2”.

Figure 3- Behaviour the three types of aluminum alloys under load apply

Table 2-Modulus of Elasticity of Aluminum Alloys for Profiles and plates

Sign ∆�� ∆�� ∙ ��

��

L-profiles 50х50х5mm

1 1 1,460 1,030 66500

2 1 1,490 1,020 65800

3 1 1,495 1,025 65260

Average 66250

Aluminium plate �~��

1 1 1,232 1,162 69850

2 1 1,236 1,170 69150

3 / / 1,200 58724

Average 65820



3. TEST SETUP

The program for experimental examinations is focused on the truss structures with aluminum

alloys, were the elements of trust are prepared with the aluminum alloys EN AW 6063 T66 ;

the aluminum plates with EN AW 6028 T651 and bolts with aluminum alloys type EN AW

6028 T6. The construction of structure is design and the structural elements are presented in

“fig.4”, with geometrical parameters and “fig.5”.[10],[5],[6].

Figure 4 Geometrical parameters of truss structure

Figure 5 Truss Structure prepared for testing

In middle span of truss structure; point 1 is fixed the pulsator for applied the cycling load

and in strain gauges are fixed in each point of structure to analyze the deformations under

cyclic vertical loads. The typical used strain gauges are with following parameters:

• Factor K=2.06 ±1.0 %

• Resistance R=120 Ω±0.35 %

• Accuracy T=0.1 %

The conditions during the setup during the all-time of examinations are laboratory

conditions with no changes. The strain Guages are connection in data logger were results are

read during the experiment.[10],[11],[4],[6].

The schematic measurements are done according to the “fig.6”, were all parameters

necessary for analyses and behavior.



Figure 6 Schematic positions of measurement points

The testing is done using the interval between maximal and minimal apply force:

�� 0,48 ∙ �%�&'()* 0,48 ∙ 90,0 43,2./

��'0 0,16 ∙ �%�&'()* 0,16 ∙ 90,0 14,4./ → ∆� 28,8./

Behaviour under loading was different for truss elements, and it’s followed by

measurements in measurements points of truss. The methodology is presented in “fig.7”.

Figure 7 Behaviour the truss elements under cyclic loads and measurements

The duration of testing was 7days and during the all-time was followed the behavior and

eventually cracks in constructions. After number of cycles / 5.9 ∙ 106 nead the ending

joint are presented the crack and deformations of plate in conection point, presented in “Fig.

8”.

Figure 8 Cracks in aluminum plates near the ending joints of structure



4. RESULTS AND DISCUSSION

Based on the results and behavior the structural element under cyclic loads: ∆� 28,8./

and the numer of cycles / 5.9 ∙ 106 too large cracks are evidently comapring with number

of cycles according to the EC 9, were the limit of cycles was limited in /7 5 ∙ 106. In

relations with nuber of cycles in “fig.9” is presented the decrease of the bearing capacity and

evidence of the fatigu of the materials.[10].

Figure 9 The behavior of the aluminum material under critical cycling load

5. CONCLUSIONS

The analyzis in model under the cyclic loadings was done according to the EC 9 and BS 8118

we can conclude:

• Compare the analytical results calculated by program STAD and experimental

examinations the results are different, because the aluminum alloys under cyclic loads

are more sensitive than analytical calculation process.

• The dynamic coefficient 89 1,6under cyclic load is more less than predicted value

under the force coefficient: 8: 2,5

• The value of parcial coeficient in fatigue effect is one of the parameter for detail

analysis ans approval such natioanal parameter.

• The result of dynamic coefficient is very imortant if we use in bridge constructions

under cyclic loads were the fatigue of materials is one of the important factor.

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aluminum alloys and behavior under cyclic loading in...

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