This project mainly focused on stress analysis of smith machine used in gymnasium.

1. MECHANICS OF MATERIALS
PROJECT REPORT
STRESS CALCULATION ON SMITH MACHINE
(GYM EQUIPMENT)
GROUP MEMBERS:
MUHAMMAD UMAR FAROOQ (2015-IM-07)
MUHAMMAD YASIR ILYAS (2015-IM-08)
SUBMITTED TO:
SIR.ADEEL SHEHZAD
INDUSTRIAL AND MANUFACTURING ENGINEERING
UNIVERSITY OF ENGINEERING AND TECHNOLGY, LAHORE

2. Abstract:
The Smith machine is a pervasive weight training apparatus, used extensively by a wide population
of weight trainers, from novices to high-level athletes. Behind each vertical post (runner) is a series
of slots on which the barbell can be hooked. This means that unlike an ordinary barbell, the Smith
machine need not be re-racked after a set of repetitions: it can be secured at any point. This
supposedly makes it safer for those who lift without a spotter, as one only needs to twist the wrist
in order to lock the barbell in place in the event that the weight becomes too great. Most models
also incorporate blocks, pegs, or other devices which can be adjusted to automatically stop the
barbell at a predetermined minimum height. This does not fully eliminate the inherent danger in
having a heavy weight on one's back To ensure that appropriate adjustments are made to the
athlete’s training regiment, the practitioner should consider the full set of findings of the present
paper.

3. Introduction:
The Smith machine is a weight machine used for weight training. It consists of
a barbell that is fixed within steel rails allowing only vertical or near-vertical movement. Some
Smith machines have the barbell counterbalanced. The machine can be used for a wide variety of
exercises though it is most commonly used to perform "Smith machine squats".
Overview:
Uniquely engineered Smith Bar provides a light starting weight combined with a large weight
capacity and exceptionally smooth, natural feel all while reducing high wear components
Equipment Features:
Instructional
placard
Squat & Bench Press with QR codes to access instructional videos
Adjustments 8 Bar hooks @ 6 in / 152.4 mm increments
Standard Features
● Adjustable safety stops easily accessed from the user position
● Six weight plate storage horns
● Foot pads and heavy duty leveler device accommodates uneven floor surfaces
Rubber Feet Yes
Equipment Specifications:
Starting Weight 68.4 lb. / 30 kg
Max Load Weight 524.4 lb. / 230 Kg Olympic Weight Plates
Weight Storage
Pins
Four Storage horns at 6 in / 15.24 cm from top to bottom length each (four per side)
Grip Diameter 1 in / 25.4 mm

4. Standard Frame
Colors
Grey
Equipment Dimensions & Weight:
Length (cm/inches) 52 in / 132.08 cm
Width (cm/inches) 1.5 in / 3.81 cm
Height (cm/inches) 72 in / 182.88 cm
Machine Weight
(base equipment)
(kg/lbs.)
342 lbs. / 150 kg
Delivery Dimensions & Weight:
Length (cm/inches) 52 in / 132.08 cm
Width (cm/inches) 1.5 in / 3.81 cm
Height (cm/inches) 72 in / 182.88 cm
Delivery Weight
(kg/lbs)
524.4 lbs / 230 kg
ADVANTAGES AND DISADVANTAGES:
Use of the Smith machine is frowned upon by many strength training devotees as it forces
the user to adopt an unnatural straight-up-and-down "bar path" which can put shear stress on the
knees or back (if squatting) or shoulders (if pressing).
The constrained movement of the bar also reduces the role that stabilizing muscles play versus an
exercise using free weights. This may allow heavier weights to be lifted, at the expense of engaging
less muscle mass overall.

5. As with other exercise machines, the Smith machine is often preferred by casual or inexperienced
strength trainees who do not know how to safely perform free weight exercises involving heavy
weights.
Many gyms cater to casual trainees and thus may provide Smith machines instead of power racks,
which are a piece of equipment critical for safely performing squats and other barbell-based free
weight exercises. As a consequence, free-weight squatting may not even be an option at many
gyms.
The Smith machine does have some advocates amongst experienced trainees, however. The "bar
path" issue is minimized for exercises involving a short range of travel such as calf
raises and shrugs. It is potentially good for performing exercise variations when progress has
slowed using other exercise forms, although care must be taken to avoid joint stress issues. The
removal of stabilizing muscles as a factor can also allow one to increase the intensity applied to
primary muscles
Practical Applications:

6. CALCULATIONS:
Ultimate stress of castiron = 𝝈 𝒖𝒍𝒕𝒊𝒎𝒂𝒕𝒆 = 𝟓𝟕 × 𝟏𝟎 𝟑
𝒑𝒔𝒊
Factorof Safety = FOS = 3
Allowable Stress = 𝝈 𝒂𝒍𝒍𝒐𝒘𝒂𝒃𝒍𝒆 = 𝟏𝟗 × 𝟏𝟎 𝟑
𝒑𝒔𝒊
Area at bottom = A = 𝟐 ×1.5
= 3 in2
Allowable load = 𝑭 𝒂𝒍𝒍𝒐𝒘𝒂𝒃𝒍𝒆 = 𝝈 𝒂𝒍𝒍𝒐𝒘𝒂𝒃𝒍𝒆 × 𝑨
= 𝟏. 𝟏𝟒 × 𝟏𝟎 𝟓
𝒍𝒃
Mass ofRod = 𝒎 𝒓𝒐𝒅 = 30 Kg

7. At ‘A’
Mass on both sides of rod = 𝑚 𝑊 = 200 Kg
Total Mass = 𝑚 𝑇 = 230 Kg
= 524.2 lb.
Stress at upper hook ‘A’ = 𝜎𝐴 =
𝐹
2×
𝜋
4
(𝑑2)
=
524.4
2×
𝜋
4
(12)
= 334.01psi
Hence, it means the stress on one side of hook is 167 psi.
At ‘B’
Mass on both sides of rod = 𝑚 𝑊 = 170 Kg
Total Mass = 𝑚 𝑇 = 200 Kg
= 456 lb.
Stress at 2nd hook ‘B’ = 𝜎 𝐵 =
456
2×
𝜋
4
(𝑑2)
=
456
2×
𝜋
4
(12)
= 290.44psi
Hence, it means the stress on one side of hook is 145.2 psi.
At ‘C’
Mass on both sides of rod = 𝑚 𝑊 = 120 Kg
Total Mass = 𝑚 𝑇 = 150 Kg
= 342 lb.
Stress at 3rd hook ‘C’ = 𝜎𝐶 =
342
2×
𝜋
4
(𝑑2)

8. =
342
2×
𝜋
4
(12)
= 217.83psi
Hence, it means the stress on one side of hook is 108.91 psi.
At ‘D’
Mass on both sides of rod = 𝑚 𝑊 = 70 Kg
Total Mass = 𝑚 𝑇 = 100 Kg
= 228 lb.
Stress at Last hook ‘D’ = 𝜎 𝐷 =
𝐹
2×
𝜋
4
(𝑑2)
=
228
2×
𝜋
4
(12)
= 145.2 psi
Hence, it means the stress on one side of hook is 72.61 psi.