Report Trip

8/10/2019 Report Trip

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1.0 Introduction

Our class subject LAS 625 Landscape Structure and Construction for 5th semester

Students of Landscape Architecture had an academic trip on 21.11.2014 and 42 students and 2

lecturers participated in that academic trip. The objective of this academic visit is to introduce

the student and technique to test the strength of timber and to complete our syllabus in this

semester. The visit is at Strength of Material Laboratory at Faculty of Mechanical Engineering.

Our trip starts on 3.00 p.m until 5.00 p.m.

Along this activity, the speaker that has been give the explanation and demonstration to

the student was an Engineer Officer of the laboratory En Azman. Before start the

demonstration, the students have been divided into two groups and have been explained and

demonstrate in two different period of time due to the size of laboratory.

2.0 Strength Test Demonstration

A universal testing machine is used to subject a material sample or structure to either

tension or compression for the purposes of experimentally determining certain engineering

properties or characteristics. These properties generally deal with the strength of a material,

ultimate or failure strength or a material or structure, or the stiffness and ductility of a material.

Materials samples may be tested for several reasons:

1.

to inspect the batch quality and consistency (e.g. wood)

2. to determine whether a given sample meets standards for its marked grading

3. to determine properties of an unknown material

Structures or scale models of structures may be tested for several reasons:

1. It is cheaper and less risky to test a scale model of a design than it is to build a full scale

prototype only to find out that the design was flawed.

2. Controlled testing conditions provide the desired data in the range of design loadings

without risking human injury and liability.

3. Testing and certification of many designs is required before a full scale structure may be

constructed.

Here are three type of test fixtures: The Bending Test,The Compression Test and lastly is The

Tension Test.


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2.1 The Bending Test (3-point bending test)

A typical application of the bending test is to gain strength and ductility information on a

brittle material, such as a timber. Bending testing is preferred for brittle materials because

surface flaws on the material or the grip of the testing machine can accidentally create unwanted

cracks that may affect test results. The flexure test creates an environment in which strength can

be measured without having to worry as much about surface flaws. Many types of Bending

testing are possible, but the most common is the 3-point flexure test, in which a sample is set

upon two supports, and a force is applied directly between the two supports. Since the forces

exerted on a material are different from a tensile test, the calculations necessary to find strength

and ductility are also different. In additions, the distance of supporting pin and the speed of

loading is effects on the bending test. There are the steps of bending process.

1. Place the sample wood on the supporting pin and make sure the

distance between that two supporting pin is suitable with the wood

size that been stated in the manual guideline British Standard


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2. After that, set up the suitable input of speed, size and dimension

of the object on the computer by followed the manual guideline

British Standard.

3. Then, switch on the machine and the loading will slowly goingdown pressing the sample wood that have place on the supporting


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4. After that, the bending process wills slowly going down until the

bending process end up and it will shows on the graph. The

maximum force is applied with the constant speed until the sample

its destruct.

5. The graph shows the maximum force is applied with constant

speed and the graph shows the sample result of bending test.


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2.2 The Compression Test

Compression testing is generally used to evaluate materials at high strain and

temperatures levels, as well as highly brittle materials for which creation of a standard tensile

specimen is very difficult. Further, it can also be used to simulate more realistic stresses on

materials that will be used for specific purposes, such as concrete. Unlike a tension test, a

compression test is performed by exerting an inward force on the material, resulting in a plastic

deformation of the material into something shorter and wider than its original form. One major

benefit to a compression test is that the sample material ideally will not experience any sort of

mechanical failure there will be no weakening such as necking experienced during the test.

Unfortunately, compression tests are not always successful in this regard. Sometimes, failure

such as buckling and barreling will weaken the specimen and create a non-uniform distributionof stress on the sample.

2.3 The Tensile Test

The tensile test is one of the most commonly used tests for evaluating materials. In its

simplest form, the tension test is accomplished by gripping opposite ends of a test item within

the load frame of a test machine. A tensile force is applied by the machine, resulting in the

gradual elongation and eventual fracture of the test item. During this process, force-extension

data, a quantitative measure of how the test item deforms under the applied tensile force, usually

are monitored and recorded. When properly conducted, the tension test provides force-extension

data that can quantify several important mechanical properties of a material. These mechanical

properties determined from tension tests include, but are not limited to, the following:

Elastic deformation properties, such as the modulus of elasticity and Poisson's ratio,

Yield strength and ultimate tensile strength,

Ductility properties, such as elongation and reduction in area, and

Strain-hardening characteristics.


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3.0 The Drop Weight Impact Machine

Drop weight impact testing is another type of low velocity testing, and it is the most

common test for composite materials. Drop weight impact tests are done to test the impact

behavior on composite plates, which most closely resemble impact damage in the field. When

using a drop weight impact tester, two categories of damage can occur. The first is clearly visible

impact damage, which can easily be seen by the naked eye. The second type of damage is barely

visible impact damage, which can seldom be seen by the naked eye. Evaluation of both types of

damage can be enhanced through the use of post-impact testing. In drop weight impact testing, a

mass is raised to a known height and released, impacting the specimen. The choice can be made

between either an instrumented or non-instrumented test machines.

3.1 The Process of Drop Weight Impact Test

A figure displaying how an instrumented impact machine works

The specimens used for drop weight testing are flat panel composite specimens. This flat

specimen is then inserted into the test machine and clamped along its edges. The clamps can be

placed in a circumferential configuration or in a rectangular configuration, based on the design

and test specifications. Once the test specimen is clamped down, the mass is raised to the desired

height, and the mass is locked into place.


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4.0 Conclusion

Based on site learning in Faculty of Mechanical Engineering, we as student of Landscape

Architecture is able to learn about how to measure strength of timber by using different methods

of test. The type and size of the timber also give the influence on strength of the timber.

Documents

Report Trip