Mohrs Circle for Strain – Lab Report Example

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The paper 'Mohr’ s Circle for Strain' is a worthy example of a lab report on formal science and physical science. Within the report presented indicates the finite element analysis (FEA) which involves the suspension of rocker arm which involves a single-seat racing car. The entire experiment tends to involve the analysis of strain in the laboratory, calculation comparison by deploying the use of the method described as Mohr’ s circle, and furthermore the validation of the part by application of the Solid Works program. Finally, the full outcomes and conclusion will be drawn from the activity and possible sources in relation to any error that may occur will be addressed. Introduction The Finite element analysis (FEA) refers to a technique that is used within computers as a method of simulating the stress and strain by the use of complex geometries (Structural Mechanics Calculators, 2014), The method is mostly applied within the process of designing or creating new products and in addition the process of refining of products that tend to exist Validation of the finite element analysis (FEA) model by using experimental Data from strain analysis.

During the stage of design, the Finite element analysis (FEA) offers guidelines to the engineer to check clearly places whereby the component may be over created, designed, or under-designed. In order for the engineer to establish a finite element analysis in a correct procedure, It’ s always advisable to update a finite element model by use of comparisons between the predicted strains and the strains that are found from the process of measuring a real component. Within the lab, the experiment highlighted bellow the finite element analysis was deployed to set up a model that included the suspension of rocker for a single-seat racing vehicle.

The model was approved by the process of gathering experimental information that was obtained from strain analysis of the rocker under the lab environment.   Experimental procedure Press Balance on the on-screen l of the P3 Strain Indicator. BALANCE MODE window opened (see Figure 2) Make sure channels 1 to 4 are set to AUTO and press Zero. This set the gauges to an initial zero. Closed the BALANCE MODE window by pressing Close. Press on the Record within the main window. Figure 3 allowing us to define how measurements are recorded Selected the Manual recording radio button.

A number of additional options appeared. Selected the radio buttons against Channels 1 to 4. Selected the ‘ On this computer’ radio button to ensure that data was saved to the computer. This action set up the data capture equipment to record and save data onto the computer. Clicked OK in the sub-window. This opened the data capture sub-window shown in Discussion Within the final activity in this laboratory experiment, the use of strain gauge rosette was very important as it was used for measuring; linear single gauge (glued underneath) played a great role as the main source of reference.   As studied from the outcomes in the table (Table 1), it indicates that the increase of the load tends to cause the increase in strain, however, immediately the load was offloaded some strain was still noticed.

It’ s also noted that the strain’ s value amounted to 0, this was due to the fact that there was no any load that was applied or put to the part, it also indicates that the apparatus needed calibration (zeroing). It’ s also noted that the strain that was calculated for the strain value for 55kg within the channel 1 amounted to 46.475μ ε .

The value that was anticipated was to be within the range of 55 and 59μ ε (for instance 50kg and 60kg). This can be elaborated by the method of calculation that is enhanced by the trend line gradient which is not very accurate hence there should be a lot of caution during the assumptions.   In cases of other channels, the obtained values of strain fitted the range that was expected. The calculated strain was enhanced and verified using the Mohr’ s circle method.

From the activity assumption that was reached upon that it was a very reliable procedure for the analysis of the strain, this was reached upon because there were very little differences within the final results. In other words, any cause of an error within the lab experiment could arise from the operator during the process of mounting the strain gauge within the surface of the component. In addition, slight misalignment from the axes may also result in different measurement results.

From the exercise, it is also evident that the strain gauge also does not display 100% as fur as the results are concerned, in most cases up to 98-99%. It was also noted that another source of error did arise from unbalanced weights, this was witnessed when the mass hanger was still swinging a little bit when the readings were taken. From the experiment the masses that were utilized the lab were old and the weight could differ 1-2% from the stated 10kg value.   The weights were mounted one on another positioning the slots at 180 degrees to each other, but only eye accuracy was used to measure this angle magnitude.

Another factor was also Room temperature this is very important as in most cases, differences in temperatures tend to affect the material of the component which may result in a display of different strain values. Conclusions From the laboratory activities and FEA, simulation outcomes tend to correlate with slight differences. It can be noted that the specified component suspension rocker arm was updated by the use of finite element analysis. It’ s also noted that the whole laboratory outcomes were successful.

There were good foundation and knowledge in regards to strain and measurement analysis of the components. We also acquired knowledge on how to apply and use the strain gauge rosette Furthermore on how to calculate first and second principal strains. We also familiarized ourselves with how to use Mohr’ s circle method and it’ s very important in relation to strain and stress calculation verification.

References

Structural Mechanics Calculators. (2014). Mohr’s Circle for strain. Retrieved from: http://math.materials-sciences.com/webMathematica/MSC/JSP/mohrCircleStrain.jsp
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