Mechanical Engineering Project: Automated Rope Releaser Design

This project proposal outlines the design and development of an automated rope releaser for drop weight impact testing. The introduction highlights the importance of understanding material responses to dynamic loading, particularly in concrete structures. The objectives focus on creating a machine that can test specimens with a maximum cross-sectional area of 8100 mm2 and vary impactor energy through adjustable height and mass. The literature review covers impact testing principles, focusing on the drop weight impact test, and discusses the limitations of manual rope release. The methodology includes project planning, design considerations, and the use of various instrumentations such as force sensors, accelerometers, and a data acquisition system. The design incorporates an automated rope release mechanism to minimize human error and ensure consistent testing. The project also explores rope management and system motor characteristics. The conclusion emphasizes the significance of the automated system in improving the accuracy and efficiency of impact testing, leading to a more reliable understanding of material behavior under dynamic loads. The project aims to provide a robust solution for impact testing, contributing to advancements in material science and structural engineering.

PROJECT PROPOSAL
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Contents
INTRODUCTION...........................................................................................................................................3
OBJECTIVES..................................................................................................................................................4
LITERATURE REVIEW....................................................................................................................................4
Impact Testing.........................................................................................................................................4
Drop Weight Impact Testing operating principle.....................................................................................6
METHODOLOGY...........................................................................................................................................8
Project Planning.......................................................................................................................................8
Design....................................................................................................................................................10
Instrumentations used..........................................................................................................................12
Force sensors.....................................................................................................................................12
Accelerometers..................................................................................................................................12
Magnetic Sensor and Magnetic strip.................................................................................................13
System of data acquisition.................................................................................................................13
Management of the rope......................................................................................................................15
Comparison of fiber rope and steel wire...............................................................................................17
Desirable Properties of rope..............................................................................................................18
Features of the proposed automatic Rope releaser..............................................................................19
Rope Management................................................................................................................................20
System Motor characteristics............................................................................................................22
CONCLUSION.............................................................................................................................................23
REFERENCES..............................................................................................................................................24

INTRODUCTION
The response of materials of concrete to the dynamic loading is usually of interest in most
of the military as well as civilian applications. The best example is like for the case of the
protective shells that are used against nuclear power plants. Such components are usually
expected to survive the loading of the impacts which are generated from the incoming missiles or
any other sources with the ability to produce such forces(Wang, Waas and Wang 2013). The
runways of the airports must be always in a position to withstand the repeated dynamic loading
which results from the takeoff of the aircraft as well as their landing. There are other examples of
dynamic loading which results from the natural hazards like earthquakes, tornadoes as well as
ocean waves. The deliberate explosion or accidental impacts are usually of great concerns. The
behavior characterization of the concrete under the impulsive loading is usually treated as the
prerequisite for all the design structures together with their analysis.
There has been the development of several techniques to assist in the study of the
mechanical properties of the structures which have been made from the concrete together with
the study of the property of the concrete itself. Consider the case of a modified impact Charpy
test that is used in the impact Charpy machine that is used by the metallurgists. The techniques
that have been illustrated above can never be used in the study of the resistant as expressed by
reinforced concretes considering that the rope releaser is manual and is subject to the accuracy of
the operator. In this particular research paper, there is a proposal of the machine design which
will specifically check on the automated rope releaser to be used in drop weight impact testing

the and thus will not be subject to the human errors. The design has therefore incorporated a
design concept which enable the rope to be released automatically during the integrity of the
specimen.
OBJECTIVES
The main aim of this particular project will be to develop as well as design an automated rope
releaser for the impact tester. The proposed machine design will be set to test specimen which
can effectively accommodate cross-sectional area maximum at 8100 mm2. The impactor energy
can be varied by changing the values of the height as well as mass sizes. The operation of the
machine will be at just a press button to have the rope and thus the weight released.
LITERATURE REVIEW
Impact Testing
Usually, when two bodies collide, there is damage caused to either one or both of them.
The ability of an object to resist damage is referred to as impact resistance. The impact test is the
measure of the amount of energy absorbed by an object to break when collides with high speed.
The impact test is an important factor to consider in many applications, for example, the safety of
products used by consumers depends on their ability to resist the breaking effect. Quantifying of
impact resistance is however difficult. Impact testing usually referred to as the toughness of the
material is about restricting the impact. It is the quantity of energy absorbed by an object to break
and is measured in joules per cubic meter (J/m3).
In a plotted graph of load versus deflection, the area under the curve is the impact energy
of breakage as shown below. In the field of construction, concrete is one of the common
materials used in modern architectures for the construction of buildings. All kinds of concrete

structures in civil engineering experience dynamic load apart from static load during the process
of design. The dynamic load may destroy the building structures and they may include explosion
load, wave load, wind load impact load, and many others. The study of concrete should be done
under impact load since the impact resistance can be used to evaluate the performance of the
concrete. Several impact tests have been carried out to determine the impact resistance of
concrete and construction materials of the same type.
The tests can be categorized into, drop-weight test, constant strain-rate test, projectile
impact test, explosive test, weighted pendulum Charpy-type impact test, instrumented pendulum
impact test, and split-Hopkinson pressure bar test depending on the mechanism of impact and
monitored parameters during the impact. Of all the above-mentioned tests, none has been
declared standard because of insufficient statistical data on the ever-changing results and
difficulty in the comparison of any two tests mentioned above.
Performing some of the tests above is difficult and therefore need sophisticated
equipment. For that reason, most scholars have committedly supported the drop-weight impact
test to determine the concrete impact resistance because it is simpler and more economical.
Nonhomogeneous concrete condition and nature of the test, however, makes the obtained results
from the test to appear scattered. Following are the summary of reasons for large variations in
the obtained results: The cylindrical specimens used in the test allow various cracks to occur
anywhere and in any direction. This makes the test more subjective and the first crack which was
made cannot be easily identified. The results are more scattered since there are no criteria for
rejected or accepted mode. Part of these errors is attributed to the errors from the manual release
of the rope. Variations in mechanical properties are therefore a factor to be considered while
determining the minimum number of required tests for measuring the properties of the materials.

Newly designed drop-weight impact test apparatus and self-designed U-shaped
concrete specimens are used to measure the concrete impact resistance as this could help
predetermine the actual place of the crack and reduce the variations in the results obtained from
the impact test. A quality control test is done by subjecting the results obtained from the impact
tests to a thorough analysis and conducting of strength tests on cubic specimens. The
relationships of ultimate failure impact resistance and the first crack are supported when the
regression technique is in use. There is also support on the minimum number of specimens in the
tests of impact resistance of the concrete in order not to increase the error.
Figure 1: Graph of load against an extension for impact load
Drop Weight Impact Testing operating principle
Principle of operation of conventional Drop Weight Impact Testing Machine
In drop weight impact testing, an object of a given weight is allowed to drop from a given
height and is accelerated by the gravitational force towards the ground. The dropped weight
causes some impact on the object it drops on which may be in the form of plastic deformation,
cracking, fracture or elastic deformation. For cases of materials made of fibers, the impact is in
the form of delamination and, or tearing of fibers. In this method of testing, the dropping weight

is directed to the targeted object by sliding it down the guide rails or through a tube. This method
of testing consisted of a mixture of doubts and surety as the weight dropped would break the
object or stops on it without any effect.
The energy for breakage of the object can, however, be estimated by increasing the height
of the drop until the point at which the dropping object will cause deformation on the targeted
material. For accuracy, various tests are being carried out on different samples. Variations can be
made on the height at which the weight drops and the mass of the weight. The impact energy is
the energy of the mass in motion at the point of collision. The energy that causes the material to
break or fracture is the energy absorbed by the material. In determining the force of impact, a
load cell is attached to the impact testing(Taraghi, Fereidoon and Taheri 2014).
Materials have different behaviors when under dynamic loading. The experimental
quantification and examination of the materials' dynamic behavior at low impact load velocities
require reliable and efficient equipment. Such impact velocities range to hundreds of m/s like
that of the bullet. The ranges are so wide that no apparatus can cover making it impossible for
testing the velocities using any apparatus. Therefore, for high-velocity impacts, devices which
are used include air gun rigs or explosive. The drop weight apparatus is used for testing impact
loads of low velocities.
In the research work which was done for drop-weight impact test, newly designed apparatus
and self-designed U-shaped specimens were used to measure the impact resistance of concrete.
In the series of tests which were done, hammers of distinct masses were used. The outcome from
the test displayed that the impact resistance results did not go by the normal distribution. The
maximum variation coefficient was found to be lower than the standard one of The American

Concrete Institute (ACI). Another research work which was done involved designing a machine
to determine the impact on composite materials. A lot of studies have been carried out on
composite materials and their impacts on laminated structures. In the process of studies and art of
designing of the numerous drop weights impact machines, the researchers came out with a
simple design machine impact. By the variation of the height of drop of the various weights, the
machine was found to have an energy impact at a projected range of 20J to 90J.
There is the development of a machine drop weight impact prototype facilitated by the analysis
which was performed through CAD software on machine tension structure. Some researchers on
their work discussed the steps to be followed in performing impact testing and the theory behind
the testing. A section of this work will give fine details on an efficient way of performing impact
tests, characteristic ways of inducing damage caused by the impact and various ways of
evaluating impact data.
Another research work was also done which dealt with the development of a dropped weight
impact testing machine. The machine was used as a facility in the experimentation of impact
loads on parts of cars or crash boxes absorbing the kinetic energy during the impact. The
machine is designed in a way that it produces the impact load to the material. It has a sensor that
measures the velocity before impact and the force that breaks the material, and a system of data
acquisition which gives record on the force breaking the object for analysis.

METHODOLOGY
Project Planning
The progress of the project development will be very smooth as well as easier with properly
defined management. It is important to have proper planning which factors insufficient resources
as well as time. The major consideration of the processes of planning will include activities like
 Knowing the timeline required for project completion
 Research procedure as well as fact-finding
 Definition of the number of available resources
 Determination of the material as well as the object that is to be used
The planning will be made before beginning the project to ensure proper construction of the drop
weight impact tester. The project considered the need to re-figure out planning at the midterm of
process. The considerations which will be put in place included the following:
 Troubleshooting procedure as well as problem-solving
 Error finding as well as making a step in the improvements
 Project testing as well as maintenance of the process.
There has been a need for taking immediate action in the project planning to ensure that all the
deliveries were made on time whenever there was a problem encounter. For example in cases
where there was a need to have initial planning taking place immediately in the acquisition of the
replaced equipment. For example in the case whereby good management, as well as proper
planning, were required for the accomplishment of the project on time.

Figure 2: Summary of the project management process of the proposed design
Design
An impact testing machine that works with automatic rope releaser was selected for the
design since it provides a controlled impact velocity by the use of the gravity. In the design, there
was a specific specimen which was fixed on top of the base which is made of the mild steel.
There was an elevation of the impactor before it could be controllably being released under the
guidance of the rope. The impactor would then hit the targeted specimen with the speed of the
impact which is actually dependent on the height of the release and the elastic properties of the
rope.
The force of the crushing on the specimen during the impact was actually sensed by the use of
the load cells whose location is between the specimen as well as the steel base. The force data on
the crushing operation would later be used in the analysis of the system numerically. It is from
the nature and requirement of such principles that the design of drop weight impact testing

machine was made. The design of the drop weight impact testing machine could be subdivided
into 4 major systems including base plate, impactor assembly which consists of the masses or the
weight sources, the guide column, the impactor head, clamp and finally the load cell that has
load cell display. The process of development of the machine includes design, fabrication and
function tests. The tests on the function of the machine which were carried out showed that the
machine could fulfill the objectives of designing the real machine. The various experiments
which were carried out using column form specimens of cross-sectional, octagonal, square and
hexagonal indicated that the results obtained from these experiments were in line with the ones
of impact simulation conducted using Finite Element Method(Nash et al .2015).
The researchers also discussed the behavior of high mass-low impact velocity reinforced
concrete beams. Various tests have been carried out on span beams and a camera oh high speed
is used to record the data about particle spallation, propagation, scabbing and formation of crack.
The load cell installed in the impactor measures the force of impact that acts on the beams(Feng,
and Aymerich 2014). A system of data logging which operates at high speeds is used to record
impact load, accelerations, strains, and others to help obtain the time histories. The research
facilitated the computational development techniques based on the combined methods of
discontinued or continuum to allow simulation of impact loaded reinforced concrete beams.
There was also research which was performed that dealt with the development of drop weight
impact test system for investigation of composite laminate impact performance. There were
developments of acquisition of data, reduction techniques of data and calibration of the system.
A test was done on the composite material plates to differentiate the performance between fabric
and cross-ply forms of materials.

Figure 3: Dimensional Sketch of the design(Feng and Aymerich 2014)
Instrumentations used
Force sensors
There is impact force that is found between the hammer tup and the specimen itself is measured
by the use of a sensor called piezoelectric force sensor. The anticipated measurement range is up
to 177.92kN. The determination of the reaction force between the specimen and the support is
through another two force sensors preferable model 203B that can give up to 89kN maximum
measurement. The sensors calibration worked with the accuracy of 0.7N.
Accelerometers
The accelerometers are mounted along the length of the beam with piezoelectric sensors whose
resonant frequency is higher than 70kHz.By considering a resolution value of 0.1g, the project